Mr. Karate/Story

Art of Fighting
When Takuma was forced to work as Geese Howard's henchman, he donned the Mr. Karate persona to protect the honor of his family and school. He was feared by many as an unbeatable and merciless opponent. Sometime during Yuri's kidnapping, he either told or left clues of his true identity to his daughter. Although he could have done the same for Ryo, Takuma decides to keep using his Mr. Karate persona when he faces his son. He was curious to see his son's true strength and didn't want their family ties to hold Ryo back. He is impressed by Ryo's progress and his real identity is revealed after his first defeat.

The King of Fighters series
Mr. Karate was later used in The King of Fighters series as comical relief. He appeared in some of the Art of Fighting Team endings, claiming that he is the true master of Kyokugenryu Karate and that Ryo, Robert and Yuri have much to learn. When they tell Takuma to take off the mask, he replies he is not Takuma Sakazaki and does not know him. He eventually takes off the mask, revealing to them what they already knew. Later, when he is hospitalized due to poor health, he humorously uses the Mr. Karate mask to sporadically sneak out of the hospital to train. King reports the stories from the hospital staff to him, and Takuma claims his innocence as usual.

SVC Chaos
His appearance in SNK vs. Capcom: SVC Chaos is probably an amalgam of the two versions. His normal form is still used for comic relief, but he also has a form called Honki ni Natta Mr. Karate, which is more serious akin to his original appearance. Mr. Karate is used as a counterpart to Akuma, and Honki ni Natta Mr. Karate serves as a counterpart to Shin Akuma.