"Anime blue hair guy" is a noun that refers to a male character in an anime series or movie who has blue hair. A prominent example of an anime blue hair guy is Kirito from the Sword Art Online series.
Anime blue hair guys are often popular with fans because they are seen as cool, mysterious, and powerful. They can also be seen as rebels or outsiders, which can make them appealing to viewers who feel like they don't fit in. One of the earliest examples of an anime blue hair guy is Goku from the Dragon Ball series, who debuted in 1984.