I am pretty thorough, so don't be annoyed if I point out a lot of issues. A lot of times they are just my opinions, so feel free to object to them. :3
d = don
k = katsu
D = big don
K = big katsu
[General]
... Kinda regret taking this request now, I have pretty much nothing to say. Mapset's very polished, especially the Oni. :3
[Muzukashii]
00:01:473 (1) - You sure you don't want this to be K? To me, it sounds kinda weird without the finish, but up to you.
00:23:639 (48) - change to d for better emphasis on 00:23:806 (49), vocal's high note
00:35:806 (100,101,102) - I would not map this part to the bells synth in the background, but to the vocals instead (since you've been mapping to the vocals a lot so far); I suggest changing this to dd
00:53:306 (161) - change to d for better emphasis on 00:53:473 (162), as well as distinguishing between vocals' different pitch at 00:53:139 (160)
01:15:889 (40) - I would personally add d here to lead in to 01:15:973 (40) for the vocals, as well as add a bit more intensity towards the end of the kiai
[Nardo's Oni]
00:01:473 (1) - like Muzu, you sure you don't want this to be K?
00:22:306 (126,127,128,129,130,131) - I would actually prefer this to be ddd ddk for two reasons:
1. 00:22:806 (131) would then be k, matching vocal's high note as well as being consistent with 00:23:139 (134,136,140)
2. The entire phrase starting from 00:21:806 would have increasing density of k notes, leading into 00:24:139 (142), the start of the next phrase.
01:01:639 (327,328) - reverse, change to kd; k would match vocals, while d would match the slight pause in the guitar
01:12:305 (409,410) - ^
[]
And that's about it! Nicely done, I like both your difficulties a lot. Hope you find this mod helpful, and good luck beatmapping! :3