Original

Toiro is the older sister of Iroha Ayukara and the crush of Fukase Kuro. She was in middle school when she died, three years older than Kuro.

She killed her parents in a fire years ago, and then died. Although her physical body was gone, the Fukase family adopted her and Iroha, and now Kuro sees hallucinations of her.

She is the one who caused Kuro's current wish for the destruction of the world.