Masaki Iwana was a Japanese voice actor, director, producer, and Butoh dancer born in Tokyo, Japan, in February 1945. He passed away on November 11, 2020. His career began in the late 1960s after a brief stint at Tokyo Broadcasting System, leaving the company in 1969 to pursue performing arts. For approximately seven years, he became known for his work as a voice actor in tokusatsu productions, a genre of live-action film and television that often features special effects and superheroes. He was particularly recognized for bringing a wide array of monster characters to life with his intellectual and refined vocal style.

Iwana's most significant voice roles were predominantly in the tokusatsu genre during the 1970s. He is famously known for his work in the Inazuman series, providing the voice for Udespa and Sadespa in Inazuman F, the sequel to the original Inazuman. The user query specifically mentions the role of Sudesper, which appears to be an alternate name or a related character to Sadespa within the Inazuman Flash continuity. Additionally, he voiced Misaildesupa in the 1974 film Tobidasu Rittai Eiga Inazuman. His other major voice credits include multiple roles in the long-running superhero series Himitsu Sentai Gorenger, where he voiced various masked characters such as Rainbow Mask, Shot Mask, Door Mask, and Iron Tube Mask. He also provided the voice for Dragon Condor in the series Condorman. While the user references the role of Masaru's Father in Inazuman Flash, the available documentation primarily confirms his extensive work voicing monster and mask characters rather than parent figures in that specific series.

Beyond his voice acting, Iwana's career was defined by his multi-faceted artistic pursuits. Voice acting was considered a secondary activity for him, as his primary passion was dance. At the age of thirty, he began serious training in Butoh, an avant-garde Japanese dance form. In 1988, he relocated to France, where he became an active Butoh dancer, director, choreographer, and producer. He established the institute for Butoh research known as La Maison du Butoh Blanc in southern Normandy. His later career focused on creating and producing theatrical films, including Vermilion Souls in 2008, A Summer Family in 2010, Princess Betrayal in 2012, and Charlotte-Susabi in 2017, where he served in roles such as director, screenwriter, and producer. His notable achievement lies in this unique transition from voicing iconic monsters in Japanese superhero television to becoming an internationally recognized figure in the world of Butoh dance and independent cinema.