Main Title: Mesu Kyoushi 4: Kegasareta Kyoudan
Official Title: 牝教師4 ~穢された教壇~
Synonym: Bitch Teacher 4: Defiled Platform, 빈교사4: 더렵혀진 교단
Type: OVA, unknown number of episodes
Year: 30.10.2015 till ?
A female teacher, Maki, who has been suspicious of Kazuya who is a sudden transfer student on a daily basis.
Looking at the attitude toward the female teacher, Miyuki Kazuya, and having a doubt about the conviction, she follows Miyuki, who is acting suspiciously, into an empty classroom.