Mari Manda’s collection centers on a recurring supernatural phenomenon: sudden, unexplained moments of shared suffocation that bind two people together for a single, frozen instant. The core premise follows high school student Akira Kanzaki, who discovers that whenever he locks eyes with his quiet classmate Yuki Shibazaki, time halts for exactly one second and both experience an overwhelming inability to breathe. During that lost heartbeat, they perceive fragments of each other’s deepest memories and unspoken emotions. What begins as a terrifying anomaly becomes an obsession, as Akira realizes these episodes occur more frequently the closer he tries to get to Yuki, and that she has been counting every single one—already past nine hundred thousand encounters.

The main characters are Akira, an outwardly cheerful but inwardly detached boy who uses humor to avoid genuine connection, and Yuki, a withdrawn girl who carries a diary filled with tallies of every suffocation event. Their dynamic is complicated by a third figure, Rei Mikage, a childhood friend of Yuki’s who initially appears protective but is later revealed to have experienced the same phenomenon with Yuki years earlier, only to have forcibly suppressed it out of fear. Rei’s presence introduces the conflict that the suffocation is not random but a side effect of a wish Yuki made as a child—to never be forgotten—which manifested as a psychic link that forces others to literally feel her internal isolation.

The setting alternates between a rain-soaked suburban town and the claustrophobic interiors of school rooftops, empty train stations, and Yuki’s childhood home, which is slowly being demolished. The narrative arcs unfold in three parts. The first arc, Tally of Seconds, follows Akira’s attempts to decode the pattern of the episodes, leading to the discovery that each suffocation swaps a single sensory memory—a taste, a scent, a sound—between the two. The second arc, The Forgotten Wisher, delves into Yuki’s past, revealing that her wish was triggered by her mother’s sudden disappearance, and that the 100-millionth suffocation will permanently erase one of the two participants from all other people’s memories. The final arc, Countdown to Zero, pits Akira against Rei, who now works to accelerate the count in order to sacrifice himself instead, believing he owes Yuki that debt. Akira instead tries to break the cycle by forcing a genuine, non-supernatural conversation with Yuki, only to realize that their last suffocation—the millionth—will occur at the exact moment she finally speaks her true feelings aloud, leaving the outcome ambiguous as to whether they merge into one consciousness or separate forever with all memories intact.