Douse Horu Nara Fukai Ana.

From Renta!:

A well-cared-for lotus spreads as far as he can see. Under the orange sunset sky, next to the quiet fields, something indecent is happening inside a small truck… After only a year, unable to adapt to the city life, Daiki's back with his parents in the countryside that he once abandoned. There, his high school crush, Goh, has married his older sister and is living with his parents. Every time Daiki pleasures himself thinking of Goh, he's consumed with self-loathing, but he can't stop. There's a guy who knows about Daiki's secret and spies on him… An understanding but aggressive guy and a guy who can't say no! An alluring heartthrob story set on a farm!!