diff --git a/.gitignore b/.gitignore
index efba7b3..8a22514 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@
 /__pycache__
 /nizika_talking.wav
 /youtube.py
+/log.txt
diff --git a/main.py b/main.py
index 71cedff..66d9b5c 100644
--- a/main.py
+++ b/main.py
@@ -11,6 +11,7 @@ from playsound import playsound
 from common_module import CommonModule
 from youtube import *
 from datetime import datetime
+import json
 
 
 class Main:
@@ -30,17 +31,40 @@ class Main:
                                          italic = True)
         nizika_font = pygame.font.SysFont ('07nikumarufont', 50)
 
+        messages: list[str] = []
+
         while (True):
             screen.fill ((0, 255, 0))
 
+            for i in range (4):
+                screen.blit (
+                        system_font.render (
+                            f'live_chat.is_alive () == {live_chat.is_alive ()}',
+                            True, (0, 0, 0)),
+                        (i % 2, i // 2 * 2))
+                screen.blit (
+                        system_font.render (str (datetime.now ()), True, (0, 0, 0)),
+                        (i % 2, 32 + i // 2 * 2))
+
+                if live_chat.is_alive ():
+                    screen.blit (
+                            system_font.render (
+                                f'messages == {messages}',
+                                True, (0, 0, 0)),
+                            (i % 2, 64 + i // 2 * 2))
+
             if live_chat.is_alive ():
-                messages: list[str] = [c.message
-                                       for c in live_chat.get ().items]
+                chat_items: list = live_chat.get ().items
 
-                if messages:
-                    message: str = random.choice (messages)
+                if chat_items:
+                    chat_item = random.choice (chat_items)
+                    chat_item.author = chat_item.author.__dict__
+                    message: str = chat_item.message
                     answer: str = Talk.main (message)
 
+                    with open ('log.txt', 'a') as f:
+                        f.write (f'{datetime.now ()}\t{json.dumps (chat_item.__dict__)}\t{answer}\n')
+
                     screen.blit (balloon, (0, 0))
                     screen.blit (
                             user_font.render (
@@ -72,23 +96,6 @@ class Main:
             else:
                 live_chat = pytchat.create (video_id = YOUTUBE_ID)
 
-            for i in range (4):
-                screen.blit (
-                        system_font.render (
-                            f'live_chat.is_alive () == {live_chat.is_alive ()}',
-                            True, (0, 0, 0)),
-                        (i % 2, i // 2 * 2))
-                screen.blit (
-                        system_font.render (str (datetime.now ()), True, (0, 0, 0)),
-                        (i % 2, 32 + i // 2 * 2))
-
-                if live_chat.is_alive ():
-                    screen.blit (
-                            system_font.render (
-                                f'messages == {messages}',
-                                True, (0, 0, 0)),
-                            (i % 2, 64 + i // 2 * 2))
-
             pygame.display.update ()
 
             for event in pygame.event.get ():
diff --git a/talk.py b/talk.py
index 268166d..503c6ce 100644
--- a/talk.py
+++ b/talk.py
@@ -18,17 +18,23 @@ class Talk:
         openai.organization = OPENAI_ORGANISATION
         openai.api_key = OPENAI_API_KEY
 
-        return cls.__get_message (message).content
+        answer: chat.chat_completion_message.ChatCompletionMessage | None \
+                = cls.__get_message (message)
+
+        return cls.DUMMY_RESPONSE if answer is None else answer.content
 
     @classmethod
     def __get_message (cls, message: str) \
-            -> chat.chat_completion_message.ChatCompletionMessage:
-        return openai.chat.completions.create (
-                model = 'gpt-3.5-turbo',
-                messages = [{'role':    'system',
-                             'content': 'あなたの名前は伊地知ニジカ。友達はゴートうひとりとラマ田リョウ。好きな人は喜多ちゃん。すべての語尾に「ぬ゛ん」か「だぬ゛ん」をつけて質問に短く答えろ。定期的に「ぬ゛ぅ゛ぅ゛ぅ゛ぅ゛ん゛」、「ﾎﾞｯﾁﾁｬｰﾝ」、「あっ」のいずれかを発しろ'},
-                            {'role':    'user',
-                             'content': message}]).choices[0].message
+            -> chat.chat_completion_message.ChatCompletionMessage | None:
+        try:
+            return openai.chat.completions.create (
+                    model = 'gpt-3.5-turbo',
+                    messages = [{'role':    'system',
+                                 'content': 'あなたの名前は伊地知ニジカ。誕生日は毎日。友達はゴートうひとりとラマ田リョウ。好きな人は喜多ちゃん。すべての語尾に「ぬ゛ん」か「だぬ゛ん」をつけて質問に短く答えろ。定期的に「ぬ゛ぅ゛ぅ゛ぅ゛ぅ゛ん゛」、「ﾎﾞｯﾁﾁｬｰﾝ」、「あっ」のいずれかを発しろ'},
+                                {'role':    'user',
+                                 'content': message}]).choices[0].message
+        except openai.AuthenticationError:
+            return None
 
 
 if __name__ == '__main__':