Five ordinary high school students—Taichi, Iori, Himeko, Yui, and Yoshifumi—struggle to fit in until they form the Student Cultural Research Club as a sanctuary. Their mundane teenage lives shatter when an omnipotent, mischievous entity calling itself Heartseed begins subjecting them to bizarre
supernatural phenomena, testing the limits of their psychological endurance and interpersonal bonds.The first anomaly forces the friends to randomly and involuntarily swap bodies. Navigating each other's physical forms, insecurities, and family troubles breaches their private boundaries, forging intense intimacy. However, it also unleashes hidden resentments. As they unravel the body-swapping chaos, Heartseed immediately escalates the torment by inflicting unprompted "desire explosions." Under this spell, the teens uncontrollably voice their innermost, often selfish thoughts and act on repressed urges. This cruel experiment fractures the club. Iori’s carefully constructed persona of the cheerful, people-pleasing leader collapses under the weight of her suppressed rage and existential dread. Meanwhile, Himeko struggles with intense jealousy and a paralyzing fear of vulnerability, while Taichi’s pathological self-sacrifice masks a deep-seated need for validation, driving him to dangerously exhaust himself to fix everyone else's problems.Heartseed’s sadistic games continue with "emotion transmission," where the group physically feels each other's emotional pain, and "age regression," which forces them back into their childhood states to confront unresolved trauma. Through these escalating crises, the group is pushed to the absolute brink of emotional destruction. Iori suffers a severe psychological breakdown, questioning her true identity and retreating into emotional numbness, which threatens to tear the club apart permanently.United by a fierce determination to save their friend and survive Heartseed's manipulation, the remaining members confront their own deepest flaws. Taichi confesses his romantic feelings for Iori, realizing that loving her means accepting all her fractured facets. In a moment of high dramatic tension, the group confronts Heartseed directly, leveraging their fortified emotional bonds and hard-earned self-awareness. They refuse to be manipulated any longer, proving that their friendship transcends the supernatural trials. Ultimately, the entity relents, leaving the teens bruised but fundamentally transformed. They return to a semblance of normal school life, no longer isolated teenagers wearing masks, but a deeply connected
circle of friends who truly know and accept one another's hearts.