Sagitter's manga / #Assassin(2)

In which our mc, the former number one assassin, gets isekaied to kill the hero. Interesting anti-hero concept, but I have a bad feeling it’ll turn into a tasteless harem.

In which mc has to go undercover at a school as a student in order to protect the principal, who is probably a prominent figure in the government. One assassin includes mc's homeroom teacher, and most days, they try and kill each other.