Hwa Jai (ホア・ジャイ, Hoa Jai; หัว ใจ in Thai language) is a character from Fatal Fury who appears as a playable character once more in The King of Fighters XIII. The producer for KOF XIII stated that he was added to be the "surprise character" for KOF fans, keeping true to their theme of not always adding popular characters for the newer cast's balance. He thought Hwa Jai would be one of the most interesting characters for an appearance in KOF due to his detailed background history and previously lone playable appearance.
A former Muay Thai champion, he was defeated by Joe. Vowing to overcome the Tiger Kick with his own Dragon Kick, he was convinced his style should be more violent and brutal to defeat his rival. Killing thugs as he trained, he was eventually shunned by the martial arts world. Noticing Geese Howard's strength, he became his subordinate soon after.
During the King of Fighters tournament, he seeks to triumph over Joe for all the despair his rival caused him since his loss. However after Joe defeats him again, he realizes that he had lost due to his weak mind and spirit. Reformed, he leaves Geese's employment and becomes good friends with Joe and supports him as Muay Thai's unbeatable champion.
He is one of the many fighters beaten by Krauser in Fatal Fury 2. Joe avenges Hwa Jai in his ending.
Hwa Jai's past employment with Geese is elaborated to have started due to him winning a tournament in Japan. After cutting his ties with Geese, he went back to his homeland. Despite what earlier accounts have implied, Hwa Jai hasn't made a comeback to the Muay Thai ring since then. Both he and Raiden were called to Southtown byKim, who believes that they are wasting their talents and need to be "reeducated". Though Hwa Jai replies that he has already abandoned his "evil ways", he is convinced by the masked wrestler that entering with the famous Kim might be a good way to revitalize his reputation to the public. Hwa Jai also wants to use this opportunity to take another shot at his rival, Joe.
Hwa Jai longs to be the best Muay Thai fighter there is. To accomplish that, he must defeat his sworn enemy Joe Higashi. After being defeated by Joe in 1992's KOF, he and Joe eventually became friends. Now, he realizes that life isn't about winning and he and Joe support each other all the time.
His KOF counterpart is rougher than his Fatal Fury counterpart, talking in a more brutal and intimidating manner. Even though he claims to have changed, he is rather cocky of his skills and is ready to start a fight at any time. His friendship with Joe has also been abandoned, thinking that he still needs to defeat his rival in a match. Considering that Raiden is "acting" like a villain in order to partake in the tournament it can't be truly ruled out that Hwa Jai isn't just faking his cruelty in King of Fighters for the sake of giving Kim something to work on.
Hwa Jai does not have any powers but when he ingests the power drink he gains above average strength, stamina and speed, but seems to lose some reflexes.
Hwa Jai uses traditional Muay Thai. Hwa Jai is only able to perform his special moves after using his "power drink". He would automatically do this after taking a significant amount of damage (around 1/3). In Fatal Fury 1 his only special move is the Dragon Kick, in the SNES version of Fatal Fury he gained another special move named "Dragon Back Breaker" and furthermore he could use that move without the effect of his power drink. KoF XIII includes version of all of his FF1 moves, the Dragon Kick, the Dragon Back Breaker and his drink power up, plus adds several other moves for Hwa Jai to use.
- King Cobra ga Yatte Kuru (King Cobra is Finally Here) - Fatal Fury
- Tame a Bad Boy - The King of Fighters XIII
- Fatal Fury — playable in the Super Nintendo version; left out of the Sega Genesis version due to memory constraints
- The King of Fighters XIII
- Garou Densetsu The Legend of Wild Wolf — one of Joe's arm wrestling opponents
- Garou Densetsu Special — one of Joe's arm wrestling opponents
- Fatal Fury 2 — listed as one of the fighters beaten by Krauser
- Fatal Fury Special — in Joe's ending
- Fatal Fury 3 — in Joe's intros; appears in the background when facing CPU Joe
- Real Bout Fatal Fury — in Joe's intros and ending
- Real Bout Fatal Fury Special — in Joe's winpose, and vs. Joe when player is Yamazaki
- Real Bout Garou Densetsu Special Dominated Mind — in the intro, fighting against Joe
- Real Bout Fatal Fury 2 — in Joe's stage
- The King of Fighters XII — as Joe's personal trainer in his profile story
- The King of Fighters 2002: Unlimited Match — background cameo
- In Fatal Fury 1 Joe's and Hwa Jai's normal attacks are different, unlike KoF XIII.
- The KOF XIII development team stated that his drink is a mixture of medicinal herbs and does not contain alcohol or cola.