Ryoji Sai is a Korean professional wrestler, mixed martial artist and promoter who currently owns and operates Pro Wrestling Land's End, where he is a former All Asia Heavyweight Champion. He is best known for working for Pro Wrestling Zero1, where he is a former two-time World Heavyweight Champion.

The World Heavyweight Championship is a professional wrestling world heavyweight championship in the Japanese promotion Pro Wrestling Zero1. It is Zero1's top singles title. It was first introduced on December 15, 2007 when Zero1 ended their relationship with the AWA Superstars of Wrestling. The AWA Superstars of Wrestling Champion at the time, Masato Tanaka, was then recognized as the first Zero1 World Heavyweight Champion. To this day, Zero1 continues to use the AWA title belt, which reads "AWA World Heavyweight Wrestling Champion", to represent their world heavyweight championship.