While Takagi and the gang are still recovering from the deadly events in the previous volume, their teacher Mr. Tsuchiya reveals his true form after questioning the potency of his "evil genes."
OK, I must admit one thing: the story in this Volume 3 was so confusing I read it absent-mindedly just in order so I can mark it as "read" in this Goodreads account. Rui Nishiwaki is still missing, being held in capture by a Nosferath inside a coffin, hidden in the basement, in a darkened room beside basketball court. Now, that underground court itself is already weird. Later on, the students found out that they were gradually forgetting Nishiwaki. That's how the coffin trick works. Anyone held captive inside it for more than 3 days, everyone will forget about him/her, as if the person never existed. How scary is that, huh?!
By the way, this manga has some nude scenes, it's not recommended for underage readers.