Orenchi no Furo Jijou #1

The four-panel manga begins with Tatsumi, a high-school boy who lives by himself. Then, a devastatingly handsome merman named Wakasa moves into the bathtub in Tatsumi's home. Wakasa is a bit self-centered but cute, while Tatsumi is cool but a busybody. The manga offers a peek into their lives together.