Kiyo, your boyfriend, died in a somewhat mysterious way–no one knows why he died; his body was just found floating in the lake of Mephistomia.

Two months after his death, your mother gave birth to a boy and also named him Kiyo.

Once Kiyo opened his eyes and saw you cradling him, he was overjoyed to see you, his girlfriend, the only thing is... He's reincarnated as your brother!