Keisaku Asano was a second-year student at Seisho Academy and Daisuke Dojima's closest friend, the sole person who understood and accepted Daisuke's hero complex. Profoundly impacted by the childhood advice "Accept everything" from Milo during a kidnapping incident, he developed a resigned outlook and often declared he had "no luck."

Within the Shibuya Defense Service, his friendly, cooperative, and upbeat personality made him the team's emotional core. He acted as a vital buffer between the self-centered Daisuke and other members, mediating conflicts and preventing internal strife. His mother, Yoshie Asano, was the only family transported with him to the future.

Severe trauma struck during the raid on the Revisions' base when he witnessed his mother's death, triggering a psychological breakdown. Unhinged and distraught, he attacked Nicholas and killed Chiharu Isurugi by crushing her head just as she attempted to time travel after transferring bodies, immediately following his mother's demise.

His soul became untethered after killing Chiharu, drifting through space and time while his physical body and piloted String Puppet petrified. His consciousness later manifested as a spectral entity with yellow eyes, appearing to Daisuke to mock or provoke him, representing unresolved trauma and connection.

Originally identified by AHRV as the prophesied individual critical to the Shibuya Drift and intended first pilot of the String Puppet, Milo defied orders and selected Daisuke instead. His later actions included two sacrifices: destroying Chiharu via suicide attack and, merged with Nicholas, preventing Nicholas from erasing Daisuke from the timeline. This merged entity wielded gravity manipulation abilities but relied on repetitive attack patterns.