Ano Hito no I ni wa Boku ga Tarinai

Makie's a boy in love, with his tall, older classmate Sachi. As a sign of his affection, he makes Sachi a special lunch every day. Sachi loves Makie, too, but she has a secret... she's actually a shapeshifting monster called a watari, and she was drawn to Makie because he smells...delicious! But it's not just Sachi who's drawn to Makie's scent, and soon, he realizes the entire monster world is after him. Fortunately, Sachi's a watari who eats watari, and she pledges to protect him. But how long can Makie survive, with Sachi's appetite the only thing between him and a monster's belly?

(Source: Kodansha USA)

Note: Chapter count includes an additional special chapter.