Masayuki is suspected of killing his ex-wife when the police find her dead. There was a message written in blood on her hand that put Masayuki at a great disadvantage. The only one who can vouch for his innocence with an alibi was Yuki-Onna, who was with him at the time of the murder. But there's no way he can let a yokai provide a statement for him. Yuki-Onna asks Kotoko for help to track down the real killer.
That's why she hid a letter 
confessing her own crimes.
.لذلك السبب خبّأت رسالة تعترف فيها بجرائمها
Deshalb hatte sie den Brief versteckt,
in dem sie auch ihre Taten gestand.
Por eso escribió la carta
confesando sus crímenes.
Por eso escribió la carta
confesando sus crímenes.
Elle a donc confessé par écrit
ses propres méfaits.
Per questo aveva nascosto una lettera 
in cui ammetteva persino la sua colpa.
Por isso ela escondeu uma carta
confessando seus crimes.
Поэтому и спрятала письмо
с признанием в своих грехах.