Ibuki Keita, a high school student plagued by a string of tragedies surrounding those close to him, distances himself from forming deep connections. However, a chance encounter with a mysterious girl named Kuro, who reveals her extraordinary powers as a Mototsumitama, shatters his skepticism. Kuro introduces Keita to the concept of 'Terra' and the enigmatic 'Doppeliner System,' pulling him into a hidden world of cosmic balance. Through a fateful contract with Kuro, Keita finds himself irrevocably linked to her, facing a future intertwined with unforeseen peril. Will Keita's already dismal fate take an even darker turn in this new reality?