Beck

Beck (ベック, Bekku) is an animal and member of the "Sacrifice Animals" whose body is situated in one of the apartments of Technopolis.

Animal File

JPN	「夜行性。サクリファイス・アニマルズのメンバー。」
ENG	"Nocturnal. A member of the Sacrifice Animals."

The Re-men may have info on where Beck is.

2nd Hint
Beck likes to practice at night.

Solution
On any night where Robo Mayor goes to Club Techno (Crescenday, Tearsday & Coinsday), the Re-men will enter his room (room 871) and leave a document on the desk, which can be read. Reading this document will display multiple rooms, including where Beck resides, room 369. Since he is nocturnal, Beck's soul only appear in his room at night.