Replay Vol 1

Yamagishi and Sendo are schoolmates, but that's about as far as their similarities go: one is a short, no-nonsense boxer, while the other is a tall, bookish conspiracy nut. But when they find themselves embroiled in a paranormal phenomenon at school involving plant-faced monster people assimilating innocent victims, it seems they'll have to set aside their differences and work together as best as they can.
Of course, it doesn't help that the only one with any answers to this bizarre situation is a mysterious "paranormal investigator" named Akisato, who insists they must find some sort of "key" to stop it all - before giant insects and other preternatural perils from the world "beyond" get to them first.