A university student, Kousaka Touki, has been inseparable from her childhood friend Shirai Eri since they were young. Along with another childhood friend, Natsume Kyoutarou, the three have shared a close bond for years. Somewhere along the way, Touki’s affection for Eri deepened into romantic love, but she has kept that secret buried, afraid that confessing would break the friendship she values above all. Everything changes when Kyoutarou finally gathers the courage to tell Eri how he feels, and the two begin dating. Touki, who had always silently endured Eri’s past romantic pursuits, is thrown into turmoil now that the relationship involves someone so central to their trio. Feeling shut out and unable to process her feelings, Touki distances herself from both Eri and Kyoutarou.

In the midst of her loneliness, Touki reconnects with Kurokawa Hisaki, a senior from her high school and the only person she ever told about her love for Eri. Hisaki, sensing Touki’s pain, proposes that she and Touki start a relationship. Touki agrees, partly to escape the jealousy and heartbreak that Eri and Kyoutarou’s relationship triggers. Yet this new relationship is complicated; Hisaki’s true motives remain ambiguous, and she seems to deliberately antagonize Eri whenever they meet.

At the same time, Eri begins to realize just how much she relies on Touki. Accustomed to being the outspoken one who always took the lead, Eri had never questioned that Touki would always be at her side. Now that Touki has withdrawn, Eri experiences a fierce possessiveness she can’t name—a feeling that blurs the line between friendship and something more. Kyoutarou, too, senses that Eri’s heart never fully turned toward him, yet he remains by her side, willing to ignore the growing distance between them.

The story weaves together the perspectives of all four characters, tracing how unspoken love, long-held secrets, and the fear of losing one another gradually reshape their relationships. Set against the backdrop of university life and the lingering memories of a shared childhood, the narrative explores the agony of wanting someone who might never see you the same way, and the quiet desperation of staying close no matter the cost.