Jaa, Kimi no Kawari ni Korosou ka? Well, Shall I Murder Instead of You?

Synopsis

The manga centers on Yuuma Fujikura, a constantly bullied first-year high school student. When a classmate named Ryou Ameri, nicknamed "Amelie," helps him out one day, Yuuma tells him not to get any more involved, or else the bullies will target Amelie too. In response to this, Amelie only tells Yuuma that he would commit murder for him if Yuuma wanted. (Source: ANN)