Re...Reisei

Nami Nakatani was once his homeroom teacher. The main character, Toru Takahashi, joins her as a backstage member of her civic orchestra. The two of them leave the launch party after the orchestra and engage in sexual intercourse in a car, which is seen by Hayano, who works at the same place....... Meanwhile, Nami is offered an introduction to the patron of a professional orchestra, and she surrenders her body to him for his convenience.

(Source: Mujin Comics, translated)

Note: Published in Comic Mugen Tensei 2023-05,06,08