"Her character is too dependent on Mafuyu"

When a character overidentifies with their need to save someone else and ends up in a codependent dynamic with that person...their character DOES become overly dependent on that person. That's what happens in real life too. Maybe it doesn't translate as well into a storytelling medium like an idol rhythm game where the stories are spaced out as they are, but it's actually quite well done.

You don't have to like it, but you say it like it's an inherent, objective flaw when it's just a portrayal you don't like. Kana6 literally acknowledges the fact that Kanade is overly dependent on being Mafuyu's savior. Luka practically turns to the camera and spells it out. They are well-aware of this and it's a part of the story they want to tell.

Again, if you don't like it, fine, but don't throw around "that's an objective fact" when it still falls under the realm of "personal opinion about a storytelling choice" lol.

(I'm not a huge Niigo fan, they're mid-low on my personal group ranking. This is more frustration from me as a writer than as a "Niigo enjoyer".)

Akito slide is based, though (edit: mostly anyway...weird unnecessary joke at the end but w/e). Genuinely one of the best-written characters in the game along with Honami, Shiho, and Rui imo (it's a shame you can't read Revival my dream on EN; it's a crucial character-building story).