Super Darling Osananajimi wa Dekiai Nikushoku Danshi: Toroama Room Share wa Osu Noudo 300%!?

After being transferred for work, the heroine ends up living with her childhood friend You, whom she hasn't seen in a long time. She remembers him as a timid, easily frightened boy who always relied on her for protection. But the You she meets again is completely different. He has grown into a tall, handsome, and intimidating man with a powerful masculine presence. When she talks about paying more rent, You unexpectedly tells her that she can "pay with her body" and pushes her down. As their relationship becomes more intimate, she discovers that he has been hiding strong feelings for her for years. You reveals that they had promised to get married when they turned 27, and that he has never been interested in anyone except her. What begins as an unexpected room share soon turns into a sweet and intense romance between two childhood friends who may have been destined for each other all along.

(Source: Shusuisha, translated)