Rio Seibu (聖舞 理王) is an energetic member of the idol group TINGS, defined by her highly expressive personality and unwavering enthusiasm for her idol career. This passion propels her drive for self-improvement and growth. While central to her character, this same intensity occasionally manifests as pushiness or stubbornness in her pursuits. Confidence in her own abilities is a core trait.

Her narrative includes a specific storyline titled "Rio Seibu Wants to be Praised," highlighting her desire for recognition. She performs alongside Haru Nabatame, Kyōka Tamaki, Yukine Gionji, and Momiji Itō. The group navigated challenges, including a period where Yukine and Momiji departed to form the duo YukiMoji before ultimately rejoining TINGS.

Rio Seibu shares a common origin with her fellow members: witnessing a concert by the renowned idol Hotaru ignited her inspiration and motivated her journey into the idol world. Her surname translates to "holy dance" (聖舞), and her given name combines the characters for "reason, logic" (理) and "king, prince, monarch, sovereign, potentate" (王).