Short answers, pulled from the story.
Akira Nishitani is a Japanese game director, game designer, and character designer, also known by the nicknames "Nin-Nin" and "Pom G". He is best known for designing Street Fighter II and Final Fight at Capcom, working alongside Akira Yasuda (Akiman).
Akira Nishitani began working at Capcom in 1986. He remained at the company until 1995, when he left to found his own studio.
Nishitani designed Street Fighter II alongside Akira Yasuda, who is known in the industry as Akiman. The two also collaborated on Final Fight.
Nishitani founded Arika in 1995 after departing Capcom. Arika's first projects were the Street Fighter EX series, which the studio developed for Capcom.
The Street Fighter EX series is a set of fighting games developed by Arika for Capcom. It was among the first work Nishitani's studio produced after he left Capcom to establish Arika in 1995.
Akira Nishitani is known by two nicknames: "Nin-Nin" and "Pom G". Both names are used to refer to him within the game development community.