Having trouble reaching rooms 28,28 and 29, 28

I started playing this game on Wii U about a week ago, it is brilliant! That said, I'm having trouble getting to the rooms at 28, 28 and 29, 28. I figure the entrance is at 28, 29, but figuring out how to bounce into that passageway is eluding me. I've been nearly everywhere else on the map, and a few places off of it. Really fun game, just getting a little frustrated with this spot.

Edit: Never mind, got lucky with random bouncing back and forth beneath the passageway. Also figured out the room at 28, 28 without too much trouble. Now I just need to figure out how to get into the room at 38, 29 and how to get the item at 35, 11. Good times!

Edit 2: Got those now, too. Found a secret passage at 38, 29 that leads off of the map. Any reason to do that before ringing the last bell, or could I come back to that later? It seems like a very tough area, so I'd rather come back to it.

The game doesn't end after you ring the last bell. The story does, but you can continue to play, going for a full map etc.

Cool, also, I just encountered a tail called Lu, it started yelling at Mi, then teleported Mi into some isolated part of the disorder. Does Lu pop up anywhere else? I wouldn't mind finding out more about it.

Hmm, don't think I've ever seen that one, but not sure.

Lu stands near an entrance to Utopioca; I think he's at 13,7, and he sells crystals. In Utopioca you can also find him, but something's not right... Aside from that, there's no story about all this in the game, maybe Nifflas had something in mind but it didn't make it in the final version.

I don't remember the full details, but at some point of the game, somebody tells that strange things can happen to people if they travel through the Disorder too often. The "Evil Lu" sequence is triggered once when you encounter Lu after you've been to the Disorder several times. Since Lu is a crystal seller, chances are she's frequently using the Disorder herself.

So normally, this encounter does make a bit of sense. It just seems a bit strange if you've never met Lu before.