Wataru is a first-year university student taking up literature. He is the bassist and lyricist for the band Argonavis, and is the younger brother of .

In stark contrast to the hot-blooded, idealistic, and optimistic Yuto, he is more cautious, realistic and pessimistic, often finding the negatives to Yuto's attempts to be positive. And yet, it's because he wants the band to be a success. He has an inferiority complex towards his older brother Kenta, and wants to surpass him.

(Source: ARGONAVIS from BanG Dream! Wiki)