Hadaka de Koi wo Kataru Naka

Kazuki, who works as a system engineer, reunites with his childhood friend Mayu, whom he has had a crush on for many years. Mayu has returned to her hometown and is helping out at her family's public bathhouse, Yomogi-yu, while also working as an illustrator. She apparently broke up with her boyfriend a year ago. Kazuki thinks this is his chance to tell her how he feels, but Mayu responds that she wants to have sex before deciding whether to date him. Since then, Kazuki has been hearing Mayu's sex stories at the bathhouse...

(Source: Natalie, translated)