ok random thing i came up with while cleaning the kitchen
what if, and hear me out, Yuu is technically as old as Lilia.
Ok my explaination for this would be (please bear with me im still all over the place with it and im tired), time in "our world" moves alot slower than it does it twst. This kinda goes with one of the plots ive come up with. It goes along the lines of a "child of the Seven" au and Alice!Yuu mixed together.
Further explaining yuu has been to Twst before when they were younger (kinda like Alice) and then they randomly stopped coming until the incident with the magic mirror. Now Yuu has met the Seven when they were younger, actually in a way the Seven looked out for Yuu while they were there (basically adopting them somehow), and kinda like OM! Yuu can "harness" the power of the Seven, but not in a "im so powerful fear me" way more like a "im so powerful that i cant even use my magic" way (idk if that makes sense).
But anyway because of this time difference Yuu can be old af in the Twst world but still very much barely and adult in ours.
I hope this makes at least some kind of sense. Like i said it was random but i hope you like it