From Nekohana:-
Meet Izumi and Tachibana. They're right in the middle of a very hot and heavy romance. Seems normal right? Except Tachibana is a teacher at Izumi's all girls high school. Calm and collected Izumi is part of the student council. Tachibana is lecherous and is always trying to find a way into Izumi's uniform. See if they can handle their hush-hush relationship and themselves.