diff --git a/yt_dlp/extractor/onsen.py b/yt_dlp/extractor/onsen.py
index 6424d7b154..bc56670859 100644
--- a/yt_dlp/extractor/onsen.py
+++ b/yt_dlp/extractor/onsen.py
@@ -21,6 +21,7 @@ class OnsenIE(InfoExtractor):
     IE_NAME = 'onsen'
     IE_DESC = 'インターネットラジオステーション＜音泉＞'
 
+    _API_HEADERS = {'X-Client': 'onsen-web'}
     _BASE_URL = 'https://www.onsen.ag'
     _HEADERS = {'Referer': f'{_BASE_URL}/'}
     _NETRC_MACHINE = 'onsen'
@@ -71,6 +72,15 @@ class OnsenIE(InfoExtractor):
         'playlist_mincount': 35,
     }]
 
+    @classmethod
+    def get_temp_id(cls, url):
+        import base64
+        import urllib.parse
+
+        if c := urllib.parse.parse_qs(urllib.parse.urlparse(url).query).get('c'):
+            return base64.urlsafe_b64decode(f'{c[-1]}===').decode()
+        return super().get_temp_id(url)
+
     @staticmethod
     def _get_encoded_id(program):
         return base64.urlsafe_b64encode(str(program['id']).encode()).decode()
@@ -80,6 +90,7 @@ class OnsenIE(InfoExtractor):
             f'{self._BASE_URL}/web_api/signin', None, 'Logging in', headers={
                 'Accept': 'application/json',
                 'Content-Type': 'application/json',
+                **self._API_HEADERS,
             }, data=json.dumps({
                 'session': {
                     'email': username,
@@ -94,7 +105,8 @@ class OnsenIE(InfoExtractor):
         program_id = self._match_id(url)
         try:
             programs = self._download_json(
-                f'{self._BASE_URL}/web_api/programs/{program_id}', program_id)
+                f'{self._BASE_URL}/web_api/programs/{program_id}',
+                program_id, headers=self._API_HEADERS)
         except ExtractorError as e:
             if isinstance(e.cause, HTTPError) and e.cause.status == 404:
                 raise ExtractorError('Invalid URL', expected=True)
@@ -103,8 +115,10 @@ class OnsenIE(InfoExtractor):
         query = {k: v[-1] for k, v in parse_qs(url).items() if v}
         if 'c' not in query:
             entries = [
-                self.url_result(update_url_query(url, {'c': self._get_encoded_id(program)}), OnsenIE)
-                for program in traverse_obj(programs, ('contents', lambda _, v: v['id']))
+                self.url_result(
+                    update_url_query(url, {'c': self._get_encoded_id(program)}),
+                    OnsenIE, str_or_none(program['id']),
+                ) for program in traverse_obj(programs, ('contents', lambda _, v: v['id']))
             ]
 
             return self.playlist_result(