Rainbow Mika (レインボー・ミカ Reinbō Mika?, R. Mika) was introduced in Street Fighter Alpha 3, which currently remains her sole playable appearance. Her real name is Mika Nanakawa (七川 美華 Nanakawa Mika?). She is a Japanese girl planning to make her debut as a professional wrestler and working very hard to achieve her dream to become "Star of the Ring". To this end, she travels the world, fighting various street fighters to promote herself and meeting her idol Zangief along the way.[32] She receives rigorous training from her manager, Yoko Harmagedon, a large muscular woman who is seen in a few of her victory poses riding a golf cart and wielding a shinai. Mika also has a cameo in the Capcom game Startling Adventures.

Mika was created to introduce a "tricky and technical character" into the series, though she was not a female wrestler in the beginning. After her development, the team introduced Karin to provide a contrast to her.[33] In the official poll by Namco, Mika has been the fifth most requested Street Fighter side character to be added to the roster of Tekken X Street Fighter, as of August 2012 raking up 14.41% of votes.