Genkaku Cool na Sensei ga Aheboteochi! (Genkaku Cool na Sensei ga Aheboteochi! (厳格クールな先生がアヘボテオチ!))

A high school student has feelings for his teacher and decides to write
her a love letter. The teacher rips the letter into pieces in front of
the class, humiliating him. Dejected, the boy visits the student nurse
to make some sense of the situation. The nurse tries to console him by
giving him some pills, and proceeds to fuck his brains out – as they all
do. The teacher walks in on this and shit hits the fan. Potential
threesome? Or murder mystery?