Sensei no Yasashii Koroshi Kata

After school, Sensei tutors me in secret. My classmates think we have some sort of relationship, but they've got it all wrong. Sensei is a serial killer, and I am his apprentice. "Sensei, please teach me how to murder." A dark love unfolds between a serial killer Sensei and his devoted apprentice!
(Source: Manga UP! Global)