I stumbled upon this game and really enjoyed it (so much so that I'm even getting it on Steam :D)!
There's this tournament called Mystery Tournament where people race a game that they've never played before... And Udongein X was played there! Because of the tournament structure, we\* didn't allow players to use the shop and they had to beat all open stages but Doremy's stage.
If you would like to check the race (the video should be timestamped, but they start talking about the game at ~13 min, and the race starts at 16:43):
\* by "we", I mean the testers... xD