this applied to every optional character in that game. Ayane had me struggling to finish off the most basic of enemies because her weapons REFUSED to cut, Momiji was better but still not as good as Ryu, Rachel was slower but with the number of enemies she was fighting it wasnt really a problem she had the power to take them down quickly which is what mattered and like i said before Marbus is a little bitch i cant believe you had trouble with that level. to call Rachel out on that while leaving the others alone is rather ridiculous.
I agree that all of those chapters can be distracting, and imo they should have been added as option mission mode-type things. But, they have varying degrees of annoyance.
My analysis of the chick levels in NGS2 (Master Ninja difficulty):
Momiji: Her chapter is fine except that going through a lot of the same areas as Ryu is a bit dull. There's also a glitch where you can get stuck and that sucks. But, it's easy for the most part, so you can whistle through it. The one challenge is the Tengus and their insta-kill, lightning-fast Izuna spams. And that is some serious bullshit.
Ayane: Ayane's level is actually fairly easy. The IS ninja fight (you know which one) is the most difficult part for sure if you're going sans items (or saving them for the boss), but once you learn the de-limb trick with her things get easier.
Rachel: Pain. Ungodly Pain. Every fight is needlessly difficult, but none so much as the butt-fucking elevator. Second-hardest segment in the game. Hopefully, you're good at UT spams and fighting your enemies while the camera looks at a random dustbin. Afterwords, you're rewarded with a fight against the revamped Mundus and his fiends, who are too fast for clumsy Rachel. Mundus is also meant to be attacked with top damage at every landing, but that's risky when you're slow and get buffer-trapped. Infinite pain.