diff --git a/apps/client/src/components/account/ProfileCard.vue b/apps/client/src/components/account/ProfileCard.vue
index d4e05b9..2ef3e63 100644
--- a/apps/client/src/components/account/ProfileCard.vue
+++ b/apps/client/src/components/account/ProfileCard.vue
@@ -63,7 +63,7 @@
                 translateGrade(formData.grade)
               }}</span>
               <span class="inset-0 right-0 pr-2 pointer-events-none absolute flex items-center justify-end">
-                <ChevronsUpDownIcon class="w-4 h-4 text-subtext" aria-hidden="true" />
+                <div class="i-lucide:lucide:chevrons-up-down w-4 h-4 text-subtext" aria-hidden="true" />
               </span>
             </ListboxButton>
             <transition
@@ -77,13 +77,18 @@
                   :key="gradeOption.grade"
                   v-slot="{ active, selected }"
                   :value="gradeOption.grade">
-                  <li :class="['py-2 px-4 pr-10 text relative cursor-default select-none', active ? 'bg-overlay' : '']">
+                  <li
+                    :class="[
+                      'py-2 px-4 pr-10 text inline-flex items-center cursor-default select-none',
+                      active ? 'bg-overlay' : '',
+                      selected ? 'text-blue-500' : '',
+                    ]">
                     <span
                       :class="['block overflow-hidden text-ellipsis whitespace-nowrap', selected ? 'font-medium' : '']">
                       {{ gradeOption.name }}
                     </span>
-                    <span v-if="selected" class="inset-0 left-0 pl-3 text-blue-500 absolute flex items-center">
-                      <CheckIcon class="w-4 h-4" aria-hidden="true" />
+                    <span v-if="selected" class="right-0 pr-6 absolute">
+                      <div class="i-lucide:check h-4 w-4 text-blue-500" aria-hidden="true" />
                     </span>
                   </li>
                 </ListboxOption>
@@ -107,7 +112,7 @@
                 translateYear(formData.year)
               }}</span>
               <span class="inset-0 right-0 pr-2 pointer-events-none absolute flex items-center justify-end">
-                <ChevronsUpDownIcon class="w-4 h-4 text-subtext" aria-hidden="true" />
+                <div class="i-lucide:lucide:chevrons-up-down w-4 h-4 text-subtext" aria-hidden="true" />
               </span>
             </ListboxButton>
             <transition
@@ -121,13 +126,18 @@
                   :key="yearOption.year"
                   v-slot="{ active, selected }"
                   :value="yearOption.year">
-                  <li :class="['py-2 px-4 pr-10 text relative cursor-default select-none', active ? 'bg-overlay' : '']">
+                  <li
+                    :class="[
+                      'py-2 px-4 pr-10 text inline-flex items-center cursor-default select-none',
+                      active ? 'bg-overlay' : '',
+                      selected ? 'text-blue-500' : '',
+                    ]">
                     <span
                       :class="['block overflow-hidden text-ellipsis whitespace-nowrap', selected ? 'font-medium' : '']">
                       {{ yearOption.name }}
                     </span>
-                    <span v-if="selected" class="inset-0 left-0 pl-3 text-blue-500 absolute flex items-center">
-                      <CheckIcon class="w-4 h-4" aria-hidden="true" />
+                    <span v-if="selected" class="right-0 pr-6 absolute">
+                      <div class="i-lucide:check h-4 w-4 text-blue-500" aria-hidden="true" />
                     </span>
                   </li>
                 </ListboxOption>
diff --git a/apps/client/src/components/account/UserHeader.vue b/apps/client/src/components/account/UserHeader.vue
index 25fa961..70f3581 100644
--- a/apps/client/src/components/account/UserHeader.vue
+++ b/apps/client/src/components/account/UserHeader.vue
@@ -18,7 +18,7 @@
         </div>
         <div class="min-w-0">
           <h2 class="text-lg font-bold text my-0 truncate">{{ user?.lastName }} {{ user?.firstName }}</h2>
-          <p class="text-base text-subtext my-0 truncate">{{ user?.username }}</p>
+          <p class="text-base text-subtext my-0 truncate">{{ user?.username ? '@' + user?.username : '' }}</p>
         </div>
       </div>
       <button type="button" class="btn-secondary px-3 py-1.5 text-sm" @click="isEditing = true">編集</button>
diff --git a/apps/client/src/components/signin/LoadingView.vue b/apps/client/src/components/signin/LoadingView.vue
new file mode 100644
index 0000000..b173e75
--- /dev/null
+++ b/apps/client/src/components/signin/LoadingView.vue
@@ -0,0 +1,22 @@
+<template>
+  <div class="h-50dvh w-full flex flex-col items-center justify-center">
+    <div class="i-lucide:loader-circle animate-spin text-2xl" aria-hidden />
+  </div>
+  <p class="text-sub text-center">
+    画面が切り替わらない場合は
+    <RouterLink :to="redirectUrl" class="text-blue-500 hover:text-blue-600 underline underline-offset-4">
+      こちら
+    </RouterLink>
+  </p>
+</template>
+
+<script setup lang="ts">
+import { RouterLink } from 'vue-router';
+
+const props = defineProps({
+  redirectUrl: {
+    type: String,
+    default: '/',
+  },
+});
+</script>
diff --git a/apps/client/src/pages/SignIn.vue b/apps/client/src/pages/SignIn.vue
index 48a2e11..3843dec 100644
--- a/apps/client/src/pages/SignIn.vue
+++ b/apps/client/src/pages/SignIn.vue
@@ -1,171 +1,142 @@
 <template>
-  <div class="p-4 flex items-center justify-center">
-    <Show when="signed-in">
-      <div class="card h-full w-full">
-        <h1 class="text-3xl font-bold text tracking-tighter text-center">Welcome Back</h1>
-        <p class="text-base text-subtext opacity-80">
-          ログインが完了しました。<br />
-          ホームへリダイレクトしています。
-        </p>
-        <div class="mt-4 mb-2 flex w-full justify-center">
-          <div class="w-48 h-3 bg-overlay1 overflow-hidden rounded-full">
-            <div
-              :style="{ width: gaugePercent + '%' }"
-              class="bg-blue-500 ease h-full transition-[width] duration-1000" />
-          </div>
-        </div>
-        <p class="text-sub">
-          画面が切り替わらない場合は
-          <RouterLink :to="redirectUrl" class="text-blue-500 hover:text-blue-600 underline underline-offset-4">
-            こちら
-          </RouterLink>
-        </p>
+  <Show when="signed-in">
+    <LoadingView :redirect-url="redirectUrl" />
+  </Show>
+
+  <Show when="signed-out">
+    <div class="card max-w-md mx-auto h-full w-full">
+      <div class="p-2">
+        <h1 class="heading-1">サインイン</h1>
       </div>
-    </Show>
-
-    <Show when="signed-out">
-      <div class="card max-w-md mx-auto h-full w-full">
-        <div class="p-2">
-          <h1 class="heading-1">サインイン</h1>
-        </div>
-        <div class="p-2 pt-0">
-          <div class="gap-6 flex flex-col">
-            <form v-if="needsVerification" @submit.prevent="handleVerifyCode">
-              <Input id="code" v-model="code" label="認証コード" name="code" required placeholder="認証コードを入力" />
-              <p class="text-sub mt-2">{{ email }} に認証コードを送信しました</p>
-
-              <div v-if="error" class="mt-4 text-base text-red-500">
-                <p>{{ error }}</p>
+      <div class="p-2 pt-0">
+        <div class="gap-6 flex flex-col">
+          <form v-if="needsVerification" @submit.prevent="handleVerifyCode">
+            <Input id="code" v-model="code" label="認証コード" name="code" required placeholder="認証コードを入力" />
+            <p class="text-sub mt-2">{{ email }} に認証コードを送信しました</p>
+
+            <div v-if="error" class="mt-4 text-base text-red-500">
+              <p>{{ error }}</p>
+            </div>
+            <button type="submit" class="btn-primary mt-4 w-full" :disabled="isLoading">
+              {{ isLoading ? '認証中...' : '認証' }}
+            </button>
+          </form>
+
+          <form v-else @submit.prevent="handleSignIn">
+            <Input
+              id="email"
+              v-model="email"
+              type="email"
+              label="メールアドレス"
+              name="email"
+              required
+              autocomplete="email"
+              placeholder="example@mail.com" />
+
+            <div class="mt-4 user-select-none">
+              <div class="mb-1.5 text-xs flex items-center">
+                <label for="password" class="form-label">パスワード</label>
+                <a
+                  href="https://accounts.omu-aikido.com/sign-in/"
+                  class="text-base text-subtext ml-auto inline-block underline underline-offset-4 hover:underline"
+                  target="_blank"
+                  rel="noopener noreferrer">
+                  パスワードを忘れた
+                </a>
               </div>
-              <button type="submit" class="btn-primary mt-4 w-full" :disabled="isLoading">
-                {{ isLoading ? '認証中...' : '認証' }}
-              </button>
-            </form>
-
-            <form v-else @submit.prevent="handleSignIn">
               <Input
-                id="email"
-                v-model="email"
-                type="email"
-                label="メールアドレス"
-                name="email"
+                id="password"
+                v-model="password"
+                type="password"
+                name="password"
                 required
-                autocomplete="email"
-                placeholder="example@mail.com" />
-
-              <div class="mt-4 user-select-none">
-                <!-- added wrapper for layout spacing if needed, though Input handles vertical gap -->
-                <!-- Password input needs custom label layout for 'Forgot Password' link?
-                      Input component has internal label. If we want the link next to label, we might need a slot or different approach.
-                      The Input component puts label above.
-                      Let's use the Input component but maybe we can't easily put the link *inside* the label line without a slot.
-                      However, the Input component doesn't have a label-right slot.
-
-                      Workaround: Don't use 'label' prop on Input, render label manually above it.
-                 -->
-                <div class="mb-1.5 text-xs flex items-center">
-                  <label for="password" class="form-label">パスワード</label>
-                  <a
-                    href="https://accounts.omu-aikido.com/sign-in/"
-                    class="text-base text-subtext ml-auto inline-block underline underline-offset-4 hover:underline"
-                    target="_blank"
-                    rel="noopener noreferrer">
-                    パスワードを忘れた
-                  </a>
-                </div>
-                <Input
-                  id="password"
-                  v-model="password"
-                  type="password"
-                  name="password"
-                  required
-                  autocomplete="current-password" />
-              </div>
-
-              <div v-if="error" class="mt-4 text-base text-red-500">
-                <p>{{ error }}</p>
-                <div class="mt-4 text-base text-subtext">
-                  サインインに失敗する場合は、
-                  <a
-                    href="https://accounts.omu-aikido.com"
-                    target="_blank"
-                    rel="noopener noreferrer"
-                    class="text-blue-500 hover:text-blue-600 underline underline-offset-4">
-                    こちら
-                  </a>
-                  からサインインをお試しください。
-                </div>
+                autocomplete="current-password" />
+            </div>
+
+            <div v-if="error" class="mt-4 text-base text-red-500">
+              <p>{{ error }}</p>
+              <div class="mt-4 text-base text-subtext">
+                サインインに失敗する場合は、
+                <a
+                  href="https://accounts.omu-aikido.com"
+                  target="_blank"
+                  rel="noopener noreferrer"
+                  class="text-blue-500 hover:text-blue-600 underline underline-offset-4">
+                  こちら
+                </a>
+                からサインインをお試しください。
               </div>
+            </div>
 
-              <button type="submit" class="btn-primary mt-6 w-full" :disabled="isLoading">
-                {{ isLoading ? 'サインイン中...' : 'サインイン' }}
-              </button>
-            </form>
-
-            <button
-              type="button"
-              class="btn text-white w-full bg-[#5865f2] hover:bg-[#4752c4]"
-              :disabled="isLoading"
-              @click="handleSignInWithDiscord">
-              <svg
-                class="sq-5 mr-2"
-                aria-hidden="true"
-                focusable="false"
-                xmlns="http://www.w3.org/2000/svg"
-                viewBox="0 0 256 256">
-                <g>
-                  <circle stroke="none" cx="96" cy="144" r="12" fill="currentColor" />
-                  <circle stroke="none" cx="160" cy="144" r="12" fill="currentColor" />
-                  <path
-                    fill="none"
-                    stroke="currentColor"
-                    stroke-linecap="round"
-                    stroke-linejoin="round"
-                    stroke-width="16"
-                    d="M74 80a175 175 0 0 1 54-8 175 175 0 0 1 54 8m0 96a175 175 0 0 1-54 8 175 175 0 0 1-54-8" />
-                  <path
-                    fill="none"
-                    stroke="currentColor"
-                    stroke-linecap="round"
-                    stroke-linejoin="round"
-                    stroke-width="16"
-                    d="m155 182 12 24a8 8 0 0 0 9 4c25-6 46-16 61-30a8 8 0 0 0 3-8L206 59a8 8 0 0 0-5-5 176 176 0 0 0-30-9 8 8 0 0 0-9 5l-8 24m-53 108-12 24a8 8 0 0 1-9 4c-25-6-46-16-61-30a8 8 0 0 1-3-8L50 59a8 8 0 0 1 5-5 176 176 0 0 1 30-9 8 8 0 0 1 9 5l8 24" />
-                </g>
-              </svg>
-              Discordで認証
+            <button type="submit" class="btn-primary mt-6 w-full" :disabled="isLoading">
+              {{ isLoading ? 'サインイン中...' : 'サインイン' }}
             </button>
-          </div>
-          <hr class="my-6" />
-          <div class="mt-4 text-base text-subtext text-center">
-            まだアカウントがありませんか?
-            <RouterLink to="/sign-up" class="text-blue-500 hover:text-blue-600 underline underline-offset-4">
-              サインアップ
-            </RouterLink>
-          </div>
+          </form>
+
+          <button
+            type="button"
+            class="btn text-white w-full bg-[#5865f2] hover:bg-[#4752c4]"
+            :disabled="isLoading"
+            @click="handleSignInWithDiscord">
+            <svg
+              class="sq-5 mr-2"
+              aria-hidden="true"
+              focusable="false"
+              xmlns="http://www.w3.org/2000/svg"
+              viewBox="0 0 256 256">
+              <g>
+                <circle stroke="none" cx="96" cy="144" r="12" fill="currentColor" />
+                <circle stroke="none" cx="160" cy="144" r="12" fill="currentColor" />
+                <path
+                  fill="none"
+                  stroke="currentColor"
+                  stroke-linecap="round"
+                  stroke-linejoin="round"
+                  stroke-width="16"
+                  d="M74 80a175 175 0 0 1 54-8 175 175 0 0 1 54 8m0 96a175 175 0 0 1-54 8 175 175 0 0 1-54-8" />
+                <path
+                  fill="none"
+                  stroke="currentColor"
+                  stroke-linecap="round"
+                  stroke-linejoin="round"
+                  stroke-width="16"
+                  d="m155 182 12 24a8 8 0 0 0 9 4c25-6 46-16 61-30a8 8 0 0 0 3-8L206 59a8 8 0 0 0-5-5 176 176 0 0 0-30-9 8 8 0 0 0-9 5l-8 24m-53 108-12 24a8 8 0 0 1-9 4c-25-6-46-16-61-30a8 8 0 0 1-3-8L50 59a8 8 0 0 1 5-5 176 176 0 0 1 30-9 8 8 0 0 1 9 5l8 24" />
+              </g>
+            </svg>
+            Discordで認証
+          </button>
+        </div>
+        <hr class="my-6" />
+        <div class="mt-4 text-base text-subtext text-center">
+          まだアカウントがありませんか?
+          <RouterLink to="/sign-up" class="text-blue-500 hover:text-blue-600 underline underline-offset-4">
+            サインアップ
+          </RouterLink>
         </div>
       </div>
-    </Show>
-  </div>
+    </div>
+  </Show>
 </template>
 
 <script setup lang="ts">
-import Input from '@/components/ui/UiInput.vue';
 import { Show } from '@clerk/vue';
-import { useAuth } from '@/composable/useAuth';
-import { useSignIn } from '@/composable/useSignIn';
 import { onMounted, ref, watch } from 'vue';
 import { useRoute, useRouter } from 'vue-router';
 
+import { useAuth } from '@/composable/useAuth';
+import { useSignIn } from '@/composable/useSignIn';
+
+import Input from '@/components/ui/UiInput.vue';
+import LoadingView from '@/components/signin/LoadingView.vue';
+
 const router = useRouter();
 const route = useRoute();
 const { email, password, code, isLoading, error, needsVerification, signIn, verifyCode, signInWithDiscord } =
   useSignIn();
 const { isAuthenticated } = useAuth();
-const gaugePercent = ref(0);
 const redirectUrl = ref('/');
 
 const handleSuccessfulSignIn = () => {
-  gaugePercent.value = 100;
   setTimeout(() => {
     router.push(redirectUrl.value);
   }, 1000);
diff --git a/apps/server/src/app/user/clerk.ts b/apps/server/src/app/user/clerk.ts
index 64a8e99..7c1ecf8 100644
--- a/apps/server/src/app/user/clerk.ts
+++ b/apps/server/src/app/user/clerk.ts
@@ -45,6 +45,7 @@ export const clerk = new Hono<{ Bindings: Env }>() //
         const updatePayload: Parameters<typeof clerkClient.users.updateUser>[1] = {};
 
         if (username && typeof username === 'string') updatePayload.username = username;
+        if (!username) updatePayload.username = '';
         if (firstName && typeof firstName === 'string') updatePayload.firstName = firstName;
         if (lastName && typeof lastName === 'string') updatePayload.lastName = lastName;
         if (Object.keys(updatePayload).length > 0) await clerkClient.users.updateUser(auth.userId, updatePayload);