A quiet classroom, the scrape of a chair, and the careful construction of yet another mask. Yano Shiki spends every school day switching personas — the athlete for the jocks, the bookworm for the honors students, whatever face the moment demands. He drifts through the halls as a ghost of a hundred borrowed selves, and no one has ever looked twice. Then Minase Akiha transfers in, sits down, and dismantles him with a single, offhand comment about the book he is reading. The one that does not fit the character he built for this room. He scrambles to cover, to deflect, to lie — and she simply walks out. The next day, something in her has shifted. She is not the same girl who sat beside him yesterday.

When he confronts her, the truth unspools faster than either of them is ready for: she harbors a second self within her body. "Akiha," the quiet, literary girl who cuts through pretense. "Haruka," the softer, warmer presence who shares the same skin. They are two distinct people occupying one life, and Shiki — a boy who has never shown anyone his real face — is suddenly the keeper of a secret that mirrors his own fractures. They make a pact in hushed voices between classes: he will help them navigate a school life where they cannot control who is fronting, and they will help him inch toward a version of himself that does not evaporate the moment someone looks away. The distance between the three of them shrinks and warps into something without a name — not quite friendship, not quite something else — and Shiki must ask whether a person who exists in halves can ever love without shattering.

Also known as: Sankaku no Kyori wa Kagirinai Zero, 三角の距離は限りないゼロ, 三角的距離無限趨近零, Sankaku no Kyori wa Kagirinai Zero.