Call of the Night manga volume 12 features story and art by Kotoyama.

Our human friends are attacked by a mysterious male vampire. Luckily - or unluckily, depending on your point of view - Ko’s half-vampire mode is growing ever more powerful. Who turned the attacker, and what is he after? No sooner are these questions answered than new ones arise as a second attacker arrives on the scene - and she’s targeting both humans and vampires!