Short answers, pulled from the story.
Enix was a Japanese multimedia publisher founded in 1975 that published video games, manga, guidebooks, and merchandise. Its best-known product was the Dragon Quest franchise, and it also published titles from studios including tri-Ace, Quintet, Chunsoft, and Tose.
Yasuhiro Fukushima founded Enix on the 22nd of September 1975 under the original name Eidansha Boshu Service Center. The subsidiary that became Enix Corporation was renamed on the 30th of August 1982.
Dragon Quest was developed after designers Yuji Horii and Koichi Nakamura, during discussions about porting The Portopia Serial Murder Case to the Famicom, decided to make an RPG instead. The game launched in 1986 with composer Koichi Sugiyama and Dragon Ball artist Akira Toriyama contributing, and sold over one million copies in Japan.
Enix expressed interest in merging with Square in 2001, citing rising game development costs. The merger completed on the 1st of April 2003, forming Square Enix, with Enix as the surviving corporate entity.
Gangan Comics is a manga imprint family launched by Enix, beginning with Monthly Shonen Gangan in March 1991. Enix created it to diversify income beyond Dragon Quest, and it published titles including Fullmetal Alchemist.
Several editors, including Yoshihiro Hosaka, left Enix in 2001 to found rival publisher Mag Garden, citing creative restrictions and tensions over Dragon Quest's dominance. Legal disputes over manga copyright followed and were resolved in 2003 when Enix agreed to partially invest in Mag Garden.