The Boy and I Who Will Break Up in 100 Days (Novel)

The Boy and I Who Will Break Up in 100 Days (Japanese: 100日後に別れる僕と彼, Hyakunichigo ni Wakareru Boku to Kare) is a Japanese literary boys' love novel published by KADOKAWA in 2023, closer to thoughtful queer fiction than to conventional romance, and the source of the 2026 MBS television drama of the same name. Yuma Kasuga and Itsuki Hasegawa are a same-sex couple who go viral without meaning to, after an interview about a partnership oath system for sexual minorities charms the internet. On the strength of that attention a production company invites them to be the subject of a documentary chronicling one hundred days of their life together, and Yuma, who genuinely wants to broaden public understanding of gay relationships, says yes.

There is one problem: by the time the cameras are ready, the two of them have already fallen apart. Yuma persuades Itsuki to keep up appearances, and they agree to perform the role of a happy couple for the lens. The documentary's director, Shiho Kayano, knows nothing of this and sets out with real conviction to capture them exactly as they are. What follows is a quietly devastating study of love performed against love felt. Yuma pushes himself to be the perfect partner; Itsuki suffocates under the weight of that expectation; and across one hundred days the distance between the story being filmed and the feelings neither man can quite bury grows harder to hold. The title tells you where the countdown is headed, but the novel is less interested in the breakup itself than in everything tangled up in it: the people who film love, the people who fake it, and the people who cannot let it go.

Beyond the central romance, the book is admired for its clear-eyed look at what LGBTQ+ people actually navigate, from everyday microaggressions to the quiet distance between the acceptance a majority offers and the equality a minority is asking for. Its structure mirrors its premise, unfolding day by day across the hundred-day shoot before closing on a handful of tender, melancholy short pieces. It was written by Asahara Naoto, who debuted in 2018 and was known for the work that became the drama Fujoshi, Ukkari Gay ni Koku., and who died of lymphoma in July 2023 at the age of thirty-eight, only weeks after this novel's release, making it his final published book. KADOKAWA issued it as a 272-page hardcover on 19 May 2023 and reissued it as a 320-page Kadokawa Bunko paperback on 25 May 2026, timed to the drama's premiere.