He's one of Ichigo and his friends' companions. With a youthful appearance and a gentle way of speaking, he sometimes unnerves Keigo with his respectful demeanor. Mizuiro has a particular fondness for older women, something Ichigo mentioned to Rukia early in the series.
As the series progresses, along with Tatsuki and Keigo, Mizuiro gains spiritual awareness and witnesses Ishida, Chad, and Ichigo departing for Hueco Mundo.
Despite his ease in attracting multiple girls at once—which makes Keigo extremely envious—Mizuiro had previously experienced feelings of loneliness and depression before befriending Ichigo and Keigo. Due to his parents' busy schedules, he rarely sees them, contributing to his introverted personality. Although Keigo was Mizuiro's first real friend, Keigo later acknowledges that Ichigo was the first person Mizuiro truly opened up to.
