In the 1992 interview with the game's designer/writer Oji Hiroi published in The Super Famicom magazine, an interviewer asked him in what ways was Tengai Makyou II an upgrade from the first game? He responded that the game cartridge could now hold 2 MB of storage. He went on to talk about how they wanted the first Tengai Makyou to be a CD-ROM game before the PC Engine system went on sale, but once they began the development, a variety of unexpected problems cropped up. They spent about a year prototyping and doing various experiments, and "for awhile it didn't seem like we were going to be able to make an RPG at all."
Contributed by ProtoSnake