Tobioriru Chokuzen no Doukyuusei ni "XXX Shiyou!" to Teian Shitemita.

Koga Gumomo is a high school girl whose striking beauty and mature demeanor set her far apart from her peers. Unfortunately, these very qualities make her the target of relentless jealousy and severe bullying from her classmates. Driven to the brink of despair by their cruelty, she finds herself standing on the edge of the school rooftop, ready to end her life. Witnessing this desperate moment, her classmate realizes he must do whatever it takes to pull her back from the ledge. In a shockingly bold move, he interrupts her tragic decision with an outrageous proposition: asking her to sleep with him. Though she reacts with immediate disgust and calls him a pervert, he refuses to back down, arguing that dying with his bizarre confession as her final memory would be a terrible way to go. He then reveals his true feelings, declaring that he loves her more than anything in the world and abruptly proposing marriage. Determined to give her a reason to live, he vows to shout his love until his dying breath if it means securing her place in the world. What follows is a wildly unconventional romantic comedy pairing the most foolishly straightforward protagonist imaginable with a cool, sullen heroine, delivering a romance overflowing with pure sweetness.