The Blue Knight shows up near the end of volume four as this mysterious guy who basically exists to protect Ichigo. He makes his first real impression during an aquarium battle with Kish, swooping in to save Ichigo when things are looking bad. He tells her straight up that he "is hers" and that he was "born to protect her"—pretty heavy stuff for a first meeting.
In the original manga, he's pretty minimal. He fights with a sword, steps in when Ichigo needs saving, and then vanishes. That's kind of his whole deal. But the anime gave him way more screen time and expanded his character way beyond those brief appearances.
Voice acting varies depending on the version: Megumi Ogata in the original Japanese anime, and Sean Schemmel for the English Mew Mew Power dub.
Content compiled by AnimeList.moe from publicly available sources.
