Hyde Kido

Hyde Kido is the protagonist of French Bread's Under Night In-Birth series, who became an In-Birth that ended up as the wielder of the legendary Insulator blade. Originally a mere second-year high school student, he was saved during a Hollow Night by Linne, current princess of the Night Blade. Due to such circumstances, he naturally owes his life to her and to eventually learn of the inner workings of his situation.

The very first crossover he has appeared in beforehand was BlazBlue: Cross Tag Battle.

Intro into Fighters World
Check out Hyde's movelist here! https://variation-force-fighters-world-crossover.wikia.com/wiki/Hyde_Kido/Fighters_World_Move_List