The Blue Knight is an unknown male who is introduced at the end of the fourth volume of the manga. During a battle with Kish at an aquarium, Ichigo is in danger of losing when the Blue Knight appears and rescues her. The Blue Knight tells Ichigo that he "is hers" and that he was "born to protect her."

In the original Tokyo Mew Mew manga, the Blue Knight initially appears only as needed to protect Ichigo—fighting with an unnamed sword and disappearing soon after.

In the anime series, the Blue Knight is given a larger role,

In the anime adaptation, his voice actor is Megumi Ogata. In the Mew Mew Power English adaptation he is voiced by Sean Schemmel.

(Source: Wikipedia)