diff --git a/.idea/deploymentTargetSelector.xml b/.idea/deploymentTargetSelector.xml
index b268ef3..2cd0598 100644
--- a/.idea/deploymentTargetSelector.xml
+++ b/.idea/deploymentTargetSelector.xml
@@ -4,6 +4,14 @@
     <selectionStates>
       <SelectionState runConfigName="app">
         <option name="selectionMode" value="DROPDOWN" />
+        <DropdownSelection timestamp="2025-12-28T12:08:49.586839600Z">
+          <Target type="DEFAULT_BOOT">
+            <handle>
+              <DeviceId pluginId="LocalEmulator" identifier="path=C:\Users\natsu\.android\avd\Pixel_8.avd" />
+            </handle>
+          </Target>
+        </DropdownSelection>
+        <DialogSelection />
       </SelectionState>
     </selectionStates>
   </component>
diff --git a/app/src/main/java/com/example/tampopo_client/views/MainActivity.java b/app/src/main/java/com/example/tampopo_client/views/MainActivity.java
index 9911876..3b52a93 100644
--- a/app/src/main/java/com/example/tampopo_client/views/MainActivity.java
+++ b/app/src/main/java/com/example/tampopo_client/views/MainActivity.java
@@ -468,20 +468,10 @@
                             if (i < 6) {
                                 i++;
                             }
-
-                            // TODO: CHANGE
-                            activitiesLiveData.observe(MainActivity.this, activities -> {
-                                if (activities == null || activities.isEmpty()) return;
-
-                                Activity latest = activities.get(activities.size() - 1);
-
-                                // UIスレッドで安全に更新
-                                FriendIconView friendView = userViews.get(friendId);
-                                if (friendView != null) {
-                                    friendView.setComment(latest.getText());
-                                    Log.d("ActivityUpdate", friendId + " のコメントを更新: " + latest.getText());
-                                }
-                            });
+                            // FriendIconView 自身が持つアクティビティ監視用 Observer を利用して
+                            // 各フレンドの最新アクティビティが更新されたタイミングで
+                            // 吹き出しコメントが自動的に変わるようにする
+                            activitiesLiveData.observe(MainActivity.this, container.getActivitiesObserver());
 
                             List<String> sortedFriendUserIds = activityViewModel.getSortedFriendUserIds();
                             int size = sortedFriendUserIds.size();