Blueberri Jin is an inmate of Contrition's Figure. During the incident in the prison, they were trapped with Korin Kim and Soft Stone, and played a sort of three-person chess game with them using one of Declan's Corrective's poems.
Later, after they saved Korin's life, the two became friends.
They are very androgynous, and wear layers of white and black cloth, wrapped around their back with white rope, with the flat of their chest exposed. They look like they’re wearing curtains, but they’re pulling it off. Their hair is back in a ponytail and they are wearing clear flats.