Short answers, pulled from the story.
Takashi Nishiyama is a Japanese video game designer, director and producer who worked at Irem, Capcom and SNK before founding the company Dimps. He is best known for designing Moon Patrol, Kung-Fu Master, Street Fighter, Fatal Fury and The King of Fighters, and for helping develop the Neo Geo system.
Takashi Nishiyama designed the 1982 scrolling shooter Moon Patrol and the 1984 beat 'em up Kung-Fu Master while at Irem. At Capcom he designed Trojan and directed the original Street Fighter, and at SNK he created the Fatal Fury franchise and helped develop the Neo Geo.
Takashi Nishiyama left Irem after Capcom's founder, Kenzo Tsujimoto, invited him to join the company during the development of Kung-Fu Master. He joined Capcom before that game was finished and was formally hired once it was released.
Takashi Nishiyama based the Hadouken on the Wave Motion Gun, an energy missile attack fired by a vessel in the 1970s anime series Space Battleship Yamato.
Takashi Nishiyama proposed the ROM cartridge design to make the Neo Geo system cheaper in markets such as China, Hong Kong, Taiwan, Southeast Asia, Central America and South America. Dedicated arcade cabinets were difficult to sell in those regions because of piracy.
Takashi Nishiyama founded the game development company Dimps in 2000 after leaving SNK. The studio later released titles including Demolish Fist, Seven Samurai 20XX, The Rumble Fish, Freedom Wars, Dragon Ball Xenoverse, Dragon Ball Xenoverse 2 and Soulcalibur VI.