Shiiko Aosoi

A student of St. Isidore University, Shiiko is hauled up in the Chemistry laboratory of her own free will, studying the effects of the pandemic. She has a fatalistic and rather cold worldview, but is shown to respect the dead and not disregard them as simple corpses.

In Otayori:

An expedition into the St. Isidore University reveals Shiiko's laboratory and a volume of her notes. Rise comments that meeting the School Live club girls changed Shiiko for the better, making her come out of her shell and stop being simply an observer to what was happening.