Kyouya Onodera

A transfer student at the school for the talented. A silent, straightforward boy who leaves others a bad impression. He often skips school.
His talent is kept secret.

His talent is being immortal. He quickly suspects Nana to be the one responsible of the others students' disappearance.

The reason why keeps his journal is because his weakness is that he only remembers the last 2 years he lived through, meaning he loses his memories of anything older than the last 2 years.