Sato

Sato or in Twilight Syndrome Murder Mystery known as E-ko, was a deceased student at Hope's Peak Academy. She killed Fuyuhiko Kuzuryu's sister and along with Mahiru Koizumi covered it up and blamed it on a fictitious serial pervert. She was killed in an act of revenge by Fuyuhiko Kuzuryu in the same way that she killed his sister. Although unconfirmed, it is possible that her talent was something relating to archery, as her character in Twilight Syndrome Murder Mystery, E-ko, mentioned being in an archery club at Hope's Peak.

A-ko, B-ko, C-ko and D-ko
In Twilight Syndrome Murder Mystery, Sato were be friends with all of them and had a very close relationship with D-ko.