In a post published on Twitter (as spotted by the research website GDRI), Tsujino paid tribute to Ieiri's long and varied career, highlighting his time illustrating for the Japanese anime magazine OUT, his work at TMS (Tokyo Movie Shinsha) and other animation companies on TV shows like RPG Densetsu Hepoi, and his contributions to both Red Company & Red Entertainment as both a character designer and director.
At Red Company / Red Entertainment, Takafumi Ieiri would work on a variety of games for PC Engine like Bonk's Adventure, Makai Prince Dorabocchan, the Wonder Boy in Monster World port/remake The Dynastic Hero, and Nemurenu Yoru no Chīsana Ohanashi, among others.
He was also the primary character designer on the Super Famicom / Super Entertainment System sequel to Makai Prince Dorabocchan, Chō Makai Taisen! Dorabocchan (which you may know in the West under the name The Twisted Tales of Spike McFang).
Our thoughts are with Ieiri's friends, family, and former co-workers during this time.