Yohei Shibusawa attends an isolated academy for those with supernatural talents, hailing from a privileged family. His father's relentless pressure to assume leadership roles fuels his perfectionism and self-important attitude. He consistently speaks with formal politeness, using "watashi" for self-reference, and reacts with stern disapproval to behaviors he deems improper—such as noisy eating, slow consumption, or uneaten rice grains.

Initially rumored among peers to stop time, his supernatural ability is formally known as "temporal regression." This power allows him to concentrate and return physically to any location within the past 24 hours, altering events to reshape the present. However, severe limitations constrain this gift: exertion escalates with regression duration, leaving him breathless after seconds and causing violent illness—including vomiting—beyond 12 hours. Eye contact after time travel instantly thrusts him back to the present. Crucially, he cannot swim.

Yohei possesses unshakable faith in his power's infallibility, believing any past change he enacts is inherently correct because he alone executes it. He views himself as the sole agent capable of "correcting" history. Within the academy, he aspires to leadership, aiming to wield his ability for what he perceives as the greater good.

His story concludes early in the series after Nana Hiiragi manipulates him by falsely claiming another student, Nanao Nakajima, was killed by an "Enemy of Humanity." Trusting Nana, Yohei uses his power to regress 24 hours before Nanao’s disappearance, intending to intervene. This leads him to a cliff above a lake. The physical toll of the time jump, compounded by his inability to swim, results in his drowning after entering the water. His body remains undiscovered when the lake surface freezes shortly afterward.