Inaho-kun wa Nise Kanojo no Hazu nanoni

Shintarou Mori, a high school freshman, is teased by those around him for wanting to spend his youth getting a girlfriend and having a sparkly high school experience. His classmate Inaho Sawatari is at the top of the class and regarded as a peerless beauty. The two of them shouldn't even be interacting, but when they're inadvertently mistaken for a couple, Inaho proposes: "How about we pretend we're really dating?" They publicly become lovers, but it turns out the most beautiful girl in the school was really an overly cute boy...!

(Source: Earth Star Entertainment, translated)