夏日 The Animation

Takeru, a married salaryman on a business trip to the countryside, meets Nazuna Tokiwa—a "gal"—through a dating app. Nazuna is a calculated "little devil" type who actively uses her charms to ensnare men. Shortly after meeting, the two engage in a passionate sexual encounter in a “sex den”—a secluded house tucked away in a remote corner of the countryside— (Source: Showten, translated)