Usokon

An ordinary girl named Yae finds herself at a crossroads at age 29, having lost both her home and job, leaving her with no place to go. However, fate intervenes when she encounters Takumi, a childhood friend, who offers an unexpected solution. He "proposes" that she move in with him in a high-rise condominium in the city, posing as his fake spouse. This sets the stage for a tale of deception centered around a handsome architect.

Official Translation: English versions are available from Kodansha, INKR, and Azuki.