[F Taku (Anma)] The plain girl who can't say no and the school principal {WitzMacher}

A weary vice-principal expecting an uneventful school trip crosses paths with a meek student locked out of her room at the inn, and one quiet night binds them together through her inability to say no. As the trip continues, her unwitting allure draws other men into the fray, forcing the older man to confront the truth behind the hold her body has on everyone around her. What begins as a single lapse in judgment spirals into a pattern neither of them seems able to escape.