Mukai (ムカイ, Mukai, also written as 無界) is the final boss in The King of Fighters 2003. His appearance was designed with the concept of petrification in mind.
He is voiced by Toshihiro Shigetsuka.
Mukai's origins are unknown. All that is know for certain is that he is a member of a secret organization, known as "Those from the Past". He is ordered to not directly intervene with the 2003 tournament, only making an appearance to test the winning team to see if they will survive "the new age". According to the KOF XI backstory, he is defeated by K' and his team.
He reappears in The King of Fighters XIII, alongside the other members of "Those from the Past", in Saiki's pre-fight sequence. While the other members withdraw, Mukai requests his master to pull back and leave the rest to him. However, Saiki instead stabs him and drains his life force completely. While Mukai's dilapidated body sinks to the ground, his master uses his energy to fight the winning team of the tournament.
He knows he is a powerful being, but he will not underestimate any opponent, even if they are human. He tends to have a very pious, almost theatrical way of speaking, with much of his dialogue being grand declarations, often speaking as if he is reciting prophecy, much like a messiah. His cohort Magaki even mockingly imitates his manner of speech in The King of Fighters XI. Unlike Magaki, however, he respects the power of humans, and is aware of their vast potential.
- Transformation - Mukai can transform from his normal form into a human-like form and vice-versa.
- Geokinesis - Mukai has the power to control earth.
- Create Earth/Rock - Mukai can create earth/rock out of nowhere.
- Modify Rock - Mukai can modify the shape of any rock.
- Petrify - By touching his opponent, Mukai can petrify them for a few moments.
- Rock Body - Mukai can cover his entire body with rock or his normal body is made of stone.
- Petrifying Blast - Mukai can fire a blast of gray energy through the air. If this blast touches anyone that is not him, that person will be petrified.
Mukai is a formidable foe adept at close or long range attacks. Up close his strikes, while relatively slow, are powerful. His basic hard kick possesses high priority and a degree of autoguard, cancelling out most physical strikes during the initial leap and leaving the victim open to the kick itself. From a distance, he can hurl rocks at foes in a basic projectile attack, ambush enemies with rising pillars (which are manually aimed by the player or CPU), or he can simply cause a pillar to fall directly on a foe, regardless of where they stand.
His Netherworld Agony fills the screen, and can be instantly followed up with another attack, adding even more damage to the formidable attack. This can be especially dangerous if Mukai has 3 or more levels of power, because he can follow this with his Desperation Move (which batters foes with a barrage of pillars), doing exorbitant amounts of damage.
- Styx - The King of Fighters 2003
- The King of Fighters '94: Rebout - background cameo in the Japan Team stage and as a statue in Rugal's stage
- The King of Fighters: Maximum Impact 2 - Nightmare Geese's Normal Outfit-Variation G