キルアオ (Series) favorite_border

[DeepL Translation - needs review] Volume 1 Introduction: Dairolf Juzo, a divorced man with a child, is a legendary assassin who was picked up by an organization when he was a child. After being stabbed by a mysterious biological weapon in an incident, Jyuuzo transforms into a junior high school student and goes to junior high school.... This is the start of a comedy about an old man in junior high school who has to start all over again as a school assassin!

(Translator: DeepL)