Souin ~Chijoku ni Somaru Trauma~

Main character is a novice teacher, but students treat him without respect. He attends a seminar where he learns that to regain self-confidence he must overcome his fear of students. Instructor dresses as school girl and taunts protagonist so that he is able to leash his anger at her and violate her. After several sessions main character is invited to become instructor himself. So here is an innocent girl who comes to his seminar, and former instructor suggests using learned methods on her...