An extrovert is someone who gains energy from social interaction. Extroverts are often loud, impulsive, socially fearless people with large groups of friends, which makes them perfect protagonists for jubilant anime shows. As a result, extroverted characters seem ever-present in popular anime.
One can find examples of extroverted anime characters in pretty much every sub-genre, from shonen series like Naruto to seinen series like Showa Genroku Rakugo Shinjuu. Often, these characters foil introverted anime protagonists, and either antagonize them or help them open up. Anime extroverts can add some much needed energy and movement to an otherwise slow series, as their bouncy nature is always fun to watch.
Naruto's extroversion may have been exacerbated by his tumultuous childhood. His parents died trying to protect their village from a nine-tailed beast, who they defeated by sealing the creature away in their newborn son's body. Naruto is the physical embodiment of a monster that brought about the deaths of hundreds, which caused him to grow up totally isolated. This may explain why he almost never wants or needs alone time when he gets older.
Kill la Kill's Mako Mankanshoku is, to put it mildly, a lot. She's a hyperactive, happy-go-lucky girl who immediately gloms onto Ryuko. She has no problem talking to absolutely anyone, and even manages to make friends with members of a group that she was previously fighting against.
Present Mic — My Hero Academia
It stands to reason that a superhero named Present Mic: The Voice Hero might be a little extroverted. This guy is one of the most outgoing characters in all of My Hero Academia; he's commonly found dancing, announcing at UA Academy events, and generally being the life of the party. While viewers don't know the specifics of his personal life, its clear that he's loud, excitable, and comfortable with just about any type of social interaction.
The club at the center of Ouran High School Host Club wouldn't exist without the absurdly extroverted Tamaki Suoh. Along with his fellow club members, Tamaki offers hosting services to his classmates. As a host, he's known for his cool, princely behavior, but around his friends, he's loud, self-centered, and flamboyant. He can often be found posing dramatically, or passionately declaring his feelings to anyone who will listen. Tamaki thrives on interactions with others, and bases nearly all of his self-worth on his social prowess.