diff --git a/core/Account/User.test.ts b/core/Account/User.test.ts
new file mode 100644
index 0000000..03aa257
--- /dev/null
+++ b/core/Account/User.test.ts
@@ -0,0 +1,32 @@
+import { IAccountRepository } from "infrastructure";
+import { Avatar, Race } from "./Avatar";
+import { Player, User } from "./User";
+
+describe("User's functionality", () => {
+  test("password hashing", () => {
+    const cases = [
+      { raw: "password", hash: "5e884898da28047151d0e56f8dc6292773603d0d6aabbdd62a11ef721d1542d8" },
+      { raw: "cello", hash: "9bbf02efd82322aadc5d06c9bcf35bb4b0e3302ca158dc800407be1a4fea67e2" },
+    ];
+
+    cases.forEach((c) => {
+      expect(User.hashPassword(c.raw)).toBe(c.hash.toLowerCase());
+    });
+  });
+});
+
+describe("Player's functionality", () => {
+  test("player level", () => {
+    [
+      { exp: 0, lv: 0 },
+      { exp: 1250, lv: 5 },
+      { exp: 5000, lv: 10 },
+    ].forEach(async (c) => {
+      const repoMock = jest.fn<Avatar, []>(() => new Avatar(Race.Egg, c.exp));
+      const p = await Player.New({ getAvatar: repoMock } as unknown as IAccountRepository, "", "");
+      const lv = p.level;
+      expect(repoMock).toBeCalledTimes(1);
+      expect(lv).toBe(c.lv);
+    });
+  });
+});
diff --git a/core/Account/User.ts b/core/Account/User.ts
index 2ef620a..f961fc6 100644
--- a/core/Account/User.ts
+++ b/core/Account/User.ts
@@ -60,21 +60,22 @@ export class LoginOptions {
 }
 
 export class Player extends User {
-  private _avatar?: Avatar;
-
-  public get avatar(): Avatar {
-    return (this._avatar = this._avatar ?? this.repo.getAvatar(this.accountId));
-  }
-
-  public set avatar(value: Avatar) {
-    this._avatar = value;
-  }
+  public avatar!: Avatar;
 
   public get level(): number {
     return this.avatar.level;
   }
 
+  /**
+   * プレイヤーをインスタンス化する場合は`New`を使ってください。
+   */
   constructor(repo: IAccountRepository, accountId: string, email: string) {
     super(repo, accountId, email);
   }
+
+  public static async New(repo: IAccountRepository, accountId: string, email: string): Promise<Player> {
+    const p = new Player(repo, accountId, email);
+    p.avatar = await p.repo.getAvatar(p.accountId);
+    return p;
+  }
 }