Long ago, humans and anthropomorphic bears lived together in harmony. But after a meteor shower struck Earth, bears worldwide turned feral and developed a craving for human flesh, sparking endless cycles of violence where bears hunted people and people fought back against bears, erasing all memory of their former peaceful coexistence. A massive barrier called the "Wall of Severance" was built to maintain peace and keep the two societies apart. Kureha Tsubaki and Sumika Izumino are a couple attending Arashigaoka Academy. Their relationship faces serious trouble when two bears manage to break through the Wall of Severance and enter the school grounds. The ravenous yet affectionate bears, Ginko Yurishiro and Lulu Yurigasaki, seem to see Kureha—who despises bears—as something more than just prey. As they grow closer to her, long-hidden secrets start to surface, secrets Kureha may find too painful to bear. When their relationships draw the attention of the Invisible Storm, a strict enforcement group within the academically rigid school, the girls are put on trial for their romantic connections. Determined to prove their love is genuine, they set out on a journey of self-discovery, aiming to reach the "promised kiss" that represents true love.