Beginning of Toire No Hanako-san　

ビギニング オブ トイレの花子さん イジメから始まる物語 (original title)

Synopsis

Hiiragi Hanako transfered to a junior high school. She was bullied by Ai, Nana and Hazuki and her secret had leaked out. She was the sole survivor from the family massacre case. While Yoshioka Aya a class teacher tried to stop bullying, Hazuki went missing. Hanako was suspected of being the criminal, but Ryouta a classmate spoke up for Hanako. And Nana disappeared.