Ru-en Rouga is an adult manga artist and illustrator originally from Fukuoka Prefecture, Japan. Working under the pen name Ruuen Rouga, which is written in kanji as 龍炎 狼牙, the creator has been active in the industry since at least the mid-1990s. Rouga is associated with several doujin circles, including Bridget Goudo, Ruu Kikaku, and SXS. The creator's real name has not been publicly disclosed.

Rouga's professional credits include work on visual novels and anime adaptations spanning from 1994 to 2015. In the visual novel medium, Rouga contributed as a staff member on Halfmoon ni Kawaru made ~Ramiya Ryou no Niji-iro Tamatebako~ in 1994, provided character design for Guardian Recall ~Shugo Juu Shoukan~ in 1996, and served as an artist for titles including Pleasure Circuit (1998), Mahou Shoujo Subaru (2009), and Furyou Shounen Nyotaika ~Ijimekko wa Choukyou Shiteshimae!~ (2015).

As an original creator, Rouga's work has been adapted into anime. The creator is credited as the original creator for the anime Matō Kitan Zankan, which was released on September 27, 1996. Another anime adaptation of Rouga's work includes Trouble Evocation, released on March 8, 1996. Original manga works by Rouga include Mukuro Hime (June 27, 2006), Nyotai-ka (2009), Trans Trans (October 19, 2012), and Tamashii no Kusari (2015), with Rouga handling both story and art for these titles. Additional manga credits include Drop of Alchemy (May 31, 2001). Rouga has also provided illustrations for novels such as Seima no Toride (June 30, 2003) and Uraniwa no Kamisama (September 1, 2006).