Momotaro Onzai is a member of the idol group Kitakore within the B-PROJECT franchise. He participates in group activities and musical releases alongside other units THRIVE, MooNs, and KiLLER KiNG. As part of Kitakore, he appears in the anime series *B-PROJECT～Kodō＊Ambitious～* (2016) and *B-PROJECT～Zecchō＊Emotion～* (2019), contributing to group performances. Kitakore's musical releases include songs such as "Koiseyo Otome," "Mysterious Kiss," and "Wonder☆Future," featuring Onzai as a group member.