Mizukamiya is a defender of Seishou Gakuen and its captain.

In Inazuma Eleven Orion no Kokuin he becomes a defender of Inazuma Japan.

In Episode 41 of Orion Nosaka and Ichihoshi jointly state that if Nosaka is the 'commander' and Ichihoshi is the ‘advisor’ of tactics then Mizukamiya is the 'library where all the information is collected'.