Kiss de Tokashita Sono Ato ni

By the decision of his parents, university student Hiro Aise is currently freeloading at the house of his friend's older brother, Mizuki Onosawa. Mizuki is a handsome accountant and the ideal husband and Hiro is basking in his good looks. At first glance, their life together is pleasant, with Hiro making meals and waking Mizuki in the mornings. But there's a problem: Hiro is romantically interested in men, and Mizuki is his first love! One day, while feeling horny, the worst happens when Mizuki sees Hiro masturbating. Even worse, everything is discovered, including his posts on social media that he's "taking applications for a boyfriend" and that he was provoked by an erotic message. However, Mizuki says something completely unexpected: "If you're that frustrated, why not have a fake romance with me?"

(Source: Ichijinsha, translated)