From xiaojiangworld:

Haruki ran away from home to visit Kotaro, the senpai whom he admires.
When Kotaro witnessed Haruki drenched with rain, he invited him into his apartment.
When Haruki told him that he likes him and plans to go to the same university, with a complicated face, Kotaro reached his hand into Haruki’s lower body.
“Either you let me do this to you or you go home quietly.”
Even though this is not what he wished for, Haruki couldn’t resist because of the pleasure.
Where will the summer affair between trust, sexual desires and pleasure lead to?
A story of hot melting sex by a perverted and cool senpai with a poker face and a small animal-looking kohai!