If you open the Doki Doki Panic instruction manual, you’re told of a storybook describing the land of Mū, where the kind of dreams people have at night determine what the weather will be the following day. The answer lies in the backstory for the game.
Whole characters not vital to gameplay got cut, and with them went the explanation for why there is no stage 7-3. The cast of characters created for that game was replaced with characters who would be familiar to Americans who played the first Super Mario Bros., but it wasn’t exactly a one-for-one substitution. 2 is a modified version of what was released in Japan as Yume Kōjō: Doki Doki Panic (夢工場 ドキドキパニック, “Dream Factory: Heart-Pounding Panic”). Of course, the game we westerners call Super Mario Bros.
