From Renta!:

On his way home from his after-school job, Ayumu Ninomiya meets a blond-haired boy who has just been accused of shoplifting. The boy, Ryosuke Nakahara, wears the same school uniform as Ayumu's younger brother, and he seems wrapped in an air of loneliness. Ayumu can't just let him go. Soon enough, they're spending more and more time together. Ayumu cares for Ryosuke like a younger brother, but what was that sudden kiss...? Ryosuke has just found love, and the target of his affection is Ayumu!