Sometimes listed as DoReMi Fantasy: Milon no DokiDoki Daibouken.
Basically it's a prequel to Milon's Secret Castle on NES. This time though it's a linear platformer. Beware, it may look cute but it's actually pretty difficult. The story begins with a big demon thing attacking the land and capturing Milon's fairy friend. Milon decides to rescue her and his parents have no problem with this for some reason. Using the untranslated version won't make much of a difference TASwise though, because all the story will be skipped with Start.
Milon can shoot bubbles, along with a few other abilities picked up along the way by collecting hidden stars in levels. These are mandatory, but they can be picked up during the first go of each run. Levels range from straightforward ones, a few mazelike ones, and a few autoscrollers, (ugh) but it's varied enough to remain interesting, and a TAS will breeze through a lot of them. Boss fights are quite hard and will be entertaining too.
It's worth a playthrough on a boring weekend. Grab the
translation patch and it'll explain pretty much everything.
Search "doremi fantasy" on youtube for some level videos and such too. Go watch the current WIP.