Korakuen Hall is a sports arena in Bunkyo, Tokyo, Japan, which has hosted boxing, professional wrestling, kickboxing, mixed martial arts and Lethwei matches.

Lethwei or Burmese boxing is a full contact combat sport from Myanmar that uses stand-up striking including headbutts. Lethwei is considered to be one of the most brutal martial arts in the world, as the sport is practiced bareknuckle with only tape and gauze while fighters are allowed to strike with their fists, elbows, knees, and feet, and the use of headbutts is also permitted. Disallowed in most combat sports, headbutts are important weapons in a Lethwei fighter's arsenal, giving Lethwei its name of the "Art of nine limbs". This, combined with its bareknuckle nature, gave Lethwei a reputation for being one of the bloodiest and most violent martial arts. Although popular throughout modern Myanmar, Lethwei has been primarily and historically associated with the Karen people of the Kayin State; vast majority of competitive Lethwei fighters are ethnolinguistically of Karen descent.