Yuito Kisaragi maintains dual lives as the popular student council president of St. Cherine Academy and the covert phantom thief Misty Knight. While preserving an ordinary school facade, he aids the Twin Angels during missions. His Misty Knight persona embodies the archetypal mysterious masked ally, wielding blue roses crafted from folded paper as weapons capable of piercing metal. He strategically intervenes at pivotal moments to protect the Twin Angels. Unbeknownst to Haruka Minazuki, one of the Twin Angels, his civilian self harbors feelings for her.

In "Twinkle Paradise," Misty Knight confronts a crisis when an explosion seemingly claims his life in episode ten. He resurfaces alive in the finale, having survived the blast through unexplained means, temporarily halting his activities before returning.

"Twin Angel Break" reveals Yuito as the older brother of Sumire Kisaragi, a new Twin Angel. His focus shifts to rescuing the incapacitated original Twin Angels, Haruka and Aoi, while obstructing antagonist Mary’s energy-coin collection. Between episodes five and six, Yuito appears brainwashed by Mary, attacking high-energy individuals to gather coins for her, causing harm. Episode eight exposes this as a calculated ruse; he feigned loyalty to infiltrate Mary’s operations, gather intelligence, and sabotage her plans undetected.

Further "Break" lore details Yuito investigating a historical feud between his Kisaragi family—messengers of Heaven—and the Amatsuki family on Meguru Amatsuki’s island. The Amatsukis, exiled as a "cursed bloodline" after betrayal, occupied a shrine originally belonging to the Kisaragis. Yuito locates this shrine and uncovers a significant box, drawing Mary’s attention—she knows both his activities and Meguru’s Twin Angel identity. Anticipating his move, Mary defeats Yuito in a confrontation, shooting him. His survival post-injury is implied but not elaborated.