Akira-kun in My Palm

Shiori is an office lady who can't get over her breakup with her boyfriend. She's been trying to forget him, but she found herself unable to move forward just yet. She felt like she could use some healing right now! That was when a palm-sized high school boy named Akira appeared before her. And he seemed to be at a loss about his mysterious condition, too. He doesn't give off the intimidating vibes of a typical man, he's more like a cute little animal... He's perfect! And that's how they started living together...!?

(Source: Shueisha, translated)