diff --git a/src/commands/item.ts b/src/commands/item.ts
new file mode 100644
index 0000000..39fcd14
--- /dev/null
+++ b/src/commands/item.ts
@@ -0,0 +1,104 @@
+import { Equipment } from "../data/proto/StarRail";
+import Player from "../db/Player";
+import ItemExcel from "../util/excel/ItemExcel";
+import Logger from "../util/Logger";
+import Interface, { Command } from "./Interface";
+const c = new Logger("/item", "blue");
+
+export default async function handle(command: Command) {
+    if (!Interface.target) {
+        c.log("No target specified");
+        return;
+    }
+
+    const player = Interface.target.player;
+    const actionType = command.args[0];
+    const itemId = Number(command.args[1]);
+
+    let count: number = 1;
+    let level: number = 1;
+    let rank: number = 1;
+    let promotion: number = 1;
+
+    for (let i = 2; i < command.args.length; i++) {
+        const arg = command.args[i];
+        const number = Number(command.args[i].substring(1));
+
+        if (arg.startsWith("x")) {
+            count = number;
+        }
+        else if (arg.startsWith("l")) {
+            level = number;
+        }
+        else if (arg.startsWith("r")) {
+            rank = number;
+        }
+        else if (arg.startsWith("p")) {
+            promotion = number;
+        }
+    }
+
+    switch (actionType) {
+        case "give": {
+            await handleGive(player, itemId, count, level, rank, promotion);
+            break;
+        }
+        case "giveall": {
+            await handleGiveAll(player);
+            break;
+        }
+        default: {
+            c.log(`Usage: /item <give|giveall> <itemId> [x<count>|l<level>|r<rank>|p<promotion>]*`);
+            break;
+        }
+    }
+}
+
+async function handleGive(player: Player, itemId: number, count:number, level: number, rank: number, promotion: number) {
+    if (!itemId) {
+        return c.log("No avatarId specified");
+    }
+
+    // Check if this item exists.
+    const itemData = ItemExcel.fromId(itemId);
+    if (!itemData) {
+        return c.log(`Item ID ${itemId} does not exist.`);
+    }
+
+    const inventory = await player.getInventory();
+    switch (itemData.ItemType) {
+        case "Material":
+            await inventory.addMaterial(itemId, count);
+            break;
+        case "Equipment":
+            for (let i = 0; i < count; i++) {
+                await inventory.addEquipment({
+                    tid: itemId,
+                    uniqueId: 0,
+                    level: level,
+                    rank: rank,
+                    exp: 1,
+                    isProtected: false,
+                    promotion: promotion,
+                    baseAvatarId: 0
+                } as Equipment);
+            }
+            break;
+        default:
+            return c.log(`Unsupported item type: ${itemData.ItemType}.`);
+            break;
+    }
+
+    c.log(`Added ${count} of item ${itemId} to player ${player.uid}`);
+}
+
+async function handleGiveAll(player: Player) {
+    const inventory = await player.getInventory();
+
+    for (const entry of ItemExcel.all()) {
+        const count = entry.ItemType == "Material" ? 100 : 1;
+        await inventory.addItem(entry.ID, count);
+    }
+
+    c.log(`All materials added to ${player.uid}`);
+}
\ No newline at end of file
diff --git a/src/db/Inventory.ts b/src/db/Inventory.ts
new file mode 100644
index 0000000..bc95e4c
--- /dev/null
+++ b/src/db/Inventory.ts
@@ -0,0 +1,369 @@
+import { Equipment, Item, Material, PlayerSyncScNotify, Relic } from "../data/proto/StarRail";
+import Logger from "../util/Logger";
+import Database from "./Database";
+import Player from "./Player";
+import ItemExcel from "../util/excel/ItemExcel";
+import { Timestamp } from "mongodb";
+
+const c = new Logger("Inventory");
+
+export interface PayItemData { 
+    id: number,
+    count: number 
+}
+
+interface InventoryI {
+    _id: number,
+    nextItemUid: number,
+    materials: { [key: number]: number },
+    relics: Relic[],
+    equipments: Equipment[]
+}
+
+export default class Inventory {
+    public readonly player : Player;
+    public readonly db: InventoryI;
+
+    private constructor(player: Player, db: InventoryI) {
+        this.player = player;
+        this.db = db;
+    }
+
+    public static async loadOrCreate(player: Player) : Promise<Inventory> {
+        // Try to load the player's inventory from the database.
+        const db = Database.getInstance();
+        const inventory = await db.get("inventory", { _id: player.uid }) as unknown as InventoryI; // How to get rid of this ugly fuck?!
+
+        // If successfull, we are done.
+        if (inventory) {
+            return new Inventory(player, inventory);
+        }
+
+        // Otherwise, we create a default inventory.
+        const data : InventoryI = {
+            _id: player.uid,
+            nextItemUid: 1,
+            materials: {},
+            relics: [],
+            equipments: []
+        };
+        await db.set("inventory", data);
+        return new Inventory(player, data);
+    }
+
+    public async save() {
+        const db = Database.getInstance();
+        await db.update("inventory", { _id: this.db._id }, this.db);
+    }
+
+    /********************************************************************************
+        Get inventory info.
+    ********************************************************************************/
+   /**
+    * Get list of all `Material`s as proto.
+    * @returns List of materials.
+    */
+    public getMaterialList() : Material[] {
+        const res: Material[] = [];
+
+        Object.keys(this.db.materials).forEach(key => {
+            res.push({ tid: Number(key), num: this.db.materials[Number(key)] } as Material);
+        });
+
+        return res;
+    }
+
+    /**
+     * Get list of all `Equipment`s as proto.
+     * @returns List of equipments.
+     */
+    public getEquipmentList() : Equipment[] {
+        return this.db.equipments;
+    }
+
+    /**
+     * Get list of all `Relic`s as proto.
+     * @returns List of relics.
+     */
+    public getRelicsList() : Relic[] {
+        return this.db.relics;
+    }
+
+    /**
+     * Returns the count of the given item (material or virtual) in the player's inventory.
+     * @param id The item id.
+     * @returns The count in the player's inventory.
+     */
+    public async getItemCount(id: number) : Promise<number> {
+        // Get item data.
+        const itemData = ItemExcel.fromId(id);
+        if (!itemData) {
+            return 0;
+        }
+
+        switch (itemData.ItemType) {
+            case "Virtual": return 0; // ToDo: Handle virtual items.
+            case "Material": return this.db.materials[id] ?? 0;
+        }
+
+        return 0;
+    }
+
+    /********************************************************************************
+        Add items to the inventory.
+    ********************************************************************************/
+
+    /**
+     * Add the given amount of the given item to the player's inventory. 
+     * @param id The item id. For equipment and relics, this is the base id.
+     * @param count The amount of items to add.
+     */
+    public async addItem(id: number, count: number) {
+        // Get info for the particular item we are trying to add.
+        const itemData = ItemExcel.fromId(id);
+        if (!itemData) {
+            return;
+        }
+
+        // Handle adding depending on item type.
+        const t = itemData.ItemType;
+        if (t == "Virtual") {
+            await this.addVirtualItem(id, count);
+        }
+        else if (t == "Material") {
+            await this.addMaterial(id, count);
+        }
+        else if (t == "Equipment") {
+            for (let i = 0; i < count; i++) {
+                await this.addEquipment(id);
+            }
+        }
+        else if (t == "Relic") {
+            for (let i = 0; i < count; i++) {
+                await this.addRelic(id);
+            }
+        }
+    }
+
+    /**
+     * Adds the given amount of the virtual item with the given id to the player's inventory.
+     * @param id The item id.
+     * @param count The amount.
+     */
+    public async addVirtualItem(id: number, count: number) {
+        // ToDo: Figure out which virtual item ID is what.
+    }
+
+    /**
+     * Adds the given amount of the material with the given id to the player's inventory.
+     * @param id The material id.
+     * @param count The amount.
+     */
+    public async addMaterial(id: number, count: number) {
+        // Get info for the particular item we are trying to add.
+        const itemData = ItemExcel.fromId(id);
+        if (!itemData || itemData.ItemType != "Material") {
+            return;
+        }
+        const t = itemData.ItemType;
+        if (t != "Material") {
+            return;
+        }
+
+        // Get current item count for this ID and calculate new count.
+        const currentCount = this.db.materials[id] ?? 0;
+        const newCount = Math.min(currentCount + count, itemData.PileLimit);
+
+        // Update.
+        this.db.materials[id] = newCount;
+        await this.save();
+
+        // Send update.
+        this.sendMaterialUpdate();
+    }
+
+    /**
+     * Adds the given equipment to the player's inventory.
+     * @param equipment Either an `Equipment`, or the base id.
+     */
+    public async addEquipment(equipment: number | Equipment) {
+        // If the parameter is a number, add a new equipment with this item ID as base.
+        if (typeof(equipment) == "number") {
+            const equip : Equipment = {
+                tid: equipment,
+                uniqueId: this.db.nextItemUid++,
+                level: 1,
+                rank: 1,
+                exp: 1,
+                isProtected: false,
+                promotion: 1,
+                baseAvatarId: 0
+            };
+
+            this.db.equipments.push(equip);
+            await this.save();
+            return;
+        }
+
+        // Otherwise, add the equipment object directly, but reset it's UID.
+        equipment.uniqueId = this.db.nextItemUid++;
+        this.db.equipments.push(equipment);
+        await this.save();
+
+        // Send update.
+        this.sendEquipmentUpdate();
+    }
+
+    /**
+     * Adds the given relic to the player's inventory.
+     * @param relic Either a `Relic`, or the base id.
+     */
+    public async addRelic(relic: number | Relic) {
+        // Don't add relics for now until we figure out affix IDs, since the game kinda breaks with
+        // incorrect ones.
+        return;
+
+        // If the parameter is a number, add a new equipment with this item ID as base.
+        /*if (typeof(relic) == "number") {
+            const rel : Relic = {
+                tid: relic,
+                uniqueId: this.db.nextItemUid++,
+                level: 1,
+                exp: 1,
+                isProtected: false,
+                baseAvatarId: 0,
+                mainAffixId: 1,
+                subAffixList: []
+            };
+
+            this.db.relics.push(rel);
+            return;
+        }
+
+        // Otherwise, add the equipment object directly, but reset it's UID.
+        relic.uniqueId = this.db.nextItemUid++;
+        this.db.relics.push(relic);*/
+    }
+
+    /********************************************************************************
+        Remove items from the inventory directly.
+    ********************************************************************************/
+
+   /**
+    * Removes the the given number of the given item (virtual or material) with the given ID.
+    * @param id The item ID.
+    * @param count The number to remove.
+    */
+    public async removeItem(id: number, count: number) {
+        const itemData = ItemExcel.fromId(id);
+        if (!itemData) {
+                return ;
+        }
+
+        switch (itemData.ItemType) {
+            case "Virtual": await this.removeVirtualItem(id, count); break;
+            case "Material": await this.removeMaterial(id, count); break;
+        }
+    }
+
+    /**
+     * Removes the given amount of the given virtual item from the player's inventory.
+     * @param id The item id.
+     * @param count The amount.
+     */
+    public async removeVirtualItem(id: number, count: number) {
+        await this.addVirtualItem(id, -count);
+    }
+
+    /**
+     * Removes the given amount of the given material from the player's inventory.
+     * @param id The item id.
+     * @param count The amount.
+     */
+    public async removeMaterial(id: number, count: number) {
+        await this.addMaterial(id, -count);
+    }
+
+    /**
+     * Removes the given equipment player's inventory.
+     * @param equipment Either an `Equipment`, or the equipment's unique id.
+     */
+    public async removeEquipment(equipment: number | Equipment) {
+        // Find index to delete.
+        const toDelete: number = (typeof(equipment) == "number") ? equipment : equipment.uniqueId;
+        const index = this.db.equipments.findIndex(i => i.uniqueId == toDelete);
+
+        // Delete and save.
+        this.db.equipments.splice(index, 1);
+        this.save();
+
+        // Send update.
+        this.sendEquipmentUpdate();
+    }
+
+    /**
+     * Removes the given relic player's inventory.
+     * @param relic Either a `Relic`, or the relic's unique id.
+     */
+    public async removeRelic(relic: number | Relic) {
+        // Find index to delete.
+        const toDelete: number = (typeof(relic) == "number") ? relic : relic.uniqueId;
+        const index = this.db.relics.findIndex(i => i.uniqueId == toDelete);
+
+        // Delete and save.
+        this.db.relics.splice(index, 1);
+        this.save();
+
+        // Send update.
+        this.sendRelicUpdate()
+    }
+
+    /********************************************************************************
+        Pay items.
+    ********************************************************************************/
+
+   /**
+    * Pay items (virtual items and materials).
+    * @param items The items to be paid.
+    * @returns True if paying succeeded, false otherwise.
+    */
+    public async payItems(items: PayItemData[]) : Promise<boolean> {
+        // Check if the player has a sufficient amount of all necessary items.
+        for (const item of items) {
+            const currentCount = await this.getItemCount(item.id);
+            if (currentCount < item.count) {
+                return false;
+            }
+        }
+
+        // We have enough of everything - pay.
+        for (const item of items) {
+            await this.removeItem(item.id, item.count);
+        }
+
+        // Send update.
+        this.sendMaterialUpdate();
+
+        // Done.
+        return true;
+    }
+
+    /********************************************************************************
+        Player updating.
+    ********************************************************************************/
+    private sendMaterialUpdate() {
+        this.player.session.send(PlayerSyncScNotify, PlayerSyncScNotify.fromPartial({
+            materialList: this.getMaterialList()
+        }));
+    }
+    private sendEquipmentUpdate() {
+        this.player.session.send(PlayerSyncScNotify, PlayerSyncScNotify.fromPartial({
+            equipmentList: this.getEquipmentList()
+        }));
+    }
+    private sendRelicUpdate() {
+        this.player.session.send(PlayerSyncScNotify, PlayerSyncScNotify.fromPartial({
+            relicList: this.getRelicsList()
+        }));
+    }
+}
\ No newline at end of file
diff --git a/src/db/Player.ts b/src/db/Player.ts
index c8ee48f..42437eb 100644
--- a/src/db/Player.ts
+++ b/src/db/Player.ts
@@ -5,6 +5,7 @@ import Account from "./Account";
 import Avatar from "./Avatar";
 import Database from "./Database";
 import { Scene } from "../game/Scene";
+import Inventory from "./Inventory";
 const c = new Logger("Player");
 
 export interface LineupI {
@@ -49,6 +50,7 @@ interface PlayerI {
 export default class Player {
     public readonly uid: number
     public readonly scene: Scene;
+    private inventory!: Inventory;
 
     private constructor(readonly session: Session, public db: PlayerI) {
         this.uid = db._id;
@@ -105,6 +107,15 @@ export default class Player {
         this.db.lineup.curIndex = curIndex;
     }
 
+    public async getInventory() : Promise<Inventory> {
+        // If this players inventory has not been loaded yet, do so now.
+        if (!this.inventory) {
+            this.inventory = await Inventory.loadOrCreate(this);
+        }
+
+        return this.inventory;
+    }
+
     public static async create(session: Session, uid: number | string): Promise<Player | undefined> {
         if (typeof uid == "string") uid = Number(uid);
         const acc = await Account.fromUID(uid);
diff --git a/src/server/kcp/Session.ts b/src/server/kcp/Session.ts
index 5a348fe..d5afad7 100644
--- a/src/server/kcp/Session.ts
+++ b/src/server/kcp/Session.ts
@@ -80,10 +80,15 @@ export default class Session {
 
     public async sync() {
         const avatars = await Avatar.fromUID(this.player.db._id);
+        const inventory = await this.player.getInventory();
+
         this.send(PlayerSyncScNotify, PlayerSyncScNotify.fromPartial({
             avatarSync: {
-                avatarList: avatars.map(x => x.data),
+                avatarList: avatars.map(x => x.data)
             },
+            materialList: inventory.getMaterialList(),
+            equipmentList: inventory.getEquipmentList(),
+            relicList: inventory.getRelicsList(),
             basicInfo: this.player.db.basicInfo
         }));
 
diff --git a/src/server/packets/DoGachaCsReq.ts b/src/server/packets/DoGachaCsReq.ts
index 05174e7..2798719 100644
--- a/src/server/packets/DoGachaCsReq.ts
+++ b/src/server/packets/DoGachaCsReq.ts
@@ -1,4 +1,5 @@
 import { DoGachaCsReq, DoGachaScRsp, GachaItem, Item, ItemList } from "../../data/proto/StarRail";
+import { PayItemData } from "../../db/Inventory";
 import Banners from "../../util/Banner";
 import Packet from "../kcp/Packet";
 import Session from "../kcp/Session";
@@ -8,6 +9,17 @@ export default async function handle(session: Session, packet: Packet) {
     const body = packet.body as DoGachaCsReq;
     const banner = Banners.config.find(banner => banner.gachaId === body.gachaId)!;
     const combined = banner.rateUpItems4.concat(banner.rateUpItems5)
+
+    // Pay currency.
+    const inventory = await session.player.getInventory();
+    const success = await inventory.payItems([{ id: banner.costItemId, count: body.gachaNum } as PayItemData]);
+
+    if (!success) {
+        session.send(DoGachaScRsp, {
+            retcode: 1
+        } as DoGachaScRsp);
+    }
+
     //bad gachaing but whatever....
     //TODO: pity system, proper logic
     for(let i = 0; i < body.gachaNum; i++){
diff --git a/src/server/packets/GetBagCsReq.ts b/src/server/packets/GetBagCsReq.ts
index 8af4f24..1693c24 100644
--- a/src/server/packets/GetBagCsReq.ts
+++ b/src/server/packets/GetBagCsReq.ts
@@ -1,12 +1,14 @@
-import { GetBagScRsp } from "../../data/proto/StarRail";
+import { Equipment, GetBagScRsp, Material, Relic } from "../../data/proto/StarRail";
 import Packet from "../kcp/Packet";
 import Session from "../kcp/Session";
 
 export default async function handle(session: Session, packet: Packet) {
+    const inventory = await session.player.getInventory();
+
     session.send(GetBagScRsp, {
-        equipmentList: [],
-        materialList: [],
-        relicList: [],
+        equipmentList: inventory.getEquipmentList(),
+        materialList: inventory.getMaterialList(),
+        relicList: inventory.getRelicsList(),
         retcode: 0,
         rogueItemList: [],
         waitDelResourceList: []
diff --git a/src/util/Banner.ts b/src/util/Banner.ts
index 91e6454..767512c 100644
--- a/src/util/Banner.ts
+++ b/src/util/Banner.ts
@@ -33,7 +33,7 @@ export default class Banners {
                 rateUpItems5: [
                     1102
                 ],
-                costItemId: -1 //unused for now
+                costItemId: 101 // Star Rail Pass
             } as Banner
         ];
 
diff --git a/src/util/excel/ItemExcel.ts b/src/util/excel/ItemExcel.ts
new file mode 100644
index 0000000..4f78af5
--- /dev/null
+++ b/src/util/excel/ItemExcel.ts
@@ -0,0 +1,20 @@
+import _ItemExcelTable from "../../data/excel/ItemExcelTable.json";
+type ItemExcelTableEntry = typeof _ItemExcelTable[keyof typeof _ItemExcelTable]
+const ItemExcelTable = _ItemExcelTable as { [key: string]: ItemExcelTableEntry };
+
+export default class ItemExcel {
+    private constructor() {
+    }
+
+    public static all() : ItemExcelTableEntry[] {
+        return Object.values(ItemExcelTable);
+    }
+
+    public static fromId(id: number) : ItemExcelTableEntry {
+        return ItemExcelTable[id];
+    }
+
+    public static fromIds(ids: number[]): ItemExcelTableEntry[] {
+        return ids.map(id => ItemExcel.fromId(id));
+    }
+}
\ No newline at end of file