Mad Hatters

The Mad Hatters (マッドハッター) is a Naruhata, Tokyo-based four-person rock group that was called to perform at the Marukane Department Store Live Event.

History
At some point, the four young men formed a rock band, which they named the "Mad Hatters." They have been noted to be skilled musicians, but it's unknown if they've ever performed at a concert as big as the Narufest.

My Hero Academia: Vigilantes
Alongside Pop☆Step, Feathers and the East Naruhata High Dance Squad, the Mad Hatters performed at their first big concert: the Narufest.

Trivia

 * According to Betten Court's Mad Hatters and East Naruhata High Dance Squad character profile, the unnamed leader was supposed to look British while Akira looked American, in terms of outfits.