Konna Otoko ni Dare ga Shita

A young teacher visits a student's home and runs into a former classmate who had vanished and now works as a debt collector for the student. A pharmaceutical salesperson offers medicine to a sick doctor in exchange for a favor, only to be recognized as someone from the doctor's past. A laid-off office worker is taken in by a sharp-witted college student for a makeover and seeks revenge on a former coworker who took his girlfriend, discovering more about the coworker than expected. An antisocial student with a dark side is locked in a room by a kind-seeming teacher who plans to end his life, and the student's resentment toward society fades under the teacher's intense fixation.