Toritsuki's sister
Gray Child aka Haiiroko which can be found inside of big jar in Jar World and standing on school balcony's staris can be big sister of Toristsuki, proof is, she actually have same haircut like Toritsuki's and almost same lenght of hair, but something goes wrong and judging by little event of her on school balcony's stairs Haiiroko made suicide, probably, how ridiculous its not sounds but her death one of reason to Toritsuki's suicide.