[Inner Oni]
00:08:097 (1,2,1,2) - I don't feel like these notes should be connected to 00:08:430 (1,1,1,1,1) - . the kdkdk fits well but feels weird to play with the connected kkdd pattern. 00:08:347 (2) - or 00:08:180 (2) - could be removed, ideally both can be removed but I'd tend to say you rather want to go with k ddkdkdk.
00:09:597 (2,1,2,1,2,1) - wouldn't you do d kkddk? d for consistency with 00:08:930 (1) - and kkddk for the holding sound in the background which is deeper at 00:09:930 - and higher at 00:10:097 - . This is also because 00:11:097 - 00:16:264 - are flipped in the follow so it'd make sense this way.
00:24:430 (1) - dkddd sounds weird to me.. that's more my view than something objective but I have the idea to change the pattern to dkkdd. It sounds imo by far more intuitive and enjoyable to play.
00:48:430 (1,2,1,2,1) - With 00:48:264 (1) - as Finisher I find you could remove 00:48:430 (1,2) - and 00:48:680 (2) - and change to 00:48:764 (1) - as Finisher note. this emphasize the song and the usage and connection to 00:48:264 (1) - much better.
01:15:930 (1,1,1,1,1) - dkdkd isn't really good at this point, at least I don't see why you would use it here. Try dkkkd (preferably) or dkkdd here.
[Oni]
00:30:264 (170,171,172) - Sounds more like kdd to follow vocals and background music properly.
[Muzukashii]
Generally, this difficulty doesn't provided many rest times which will be exhausting for players to keep track while playing. Oni uses dozen of 1/2 breaks and isn't too continously mapped - good thing for the Muzukashii so it can use 1/1 breaks.
suggesting removals for following parts:
00:08:097 (31) -
00:13:430 (57) -
00:21:264 (91,92) -
00:29:430 (128) -
00:37:264 (161,162,163,164) -
00:49:264 (27,28) -
00:59:680 (75,76,77) -
01:07:764 (111,112,113) -
These are raw examples, you can make your own and adjust the difficulty so you have breaks but still keeping the flow.
[Futsuu]
Although the BPM is on 180, I don't find we need to use 1.20x. Just stick with 1.40x (same for Kantan).
00:26:097 (62) - What about a longer break here? After you've adjusted Muzukashii to have more and longer break times you should provide some even longer for Futsuu then.
00:31:264 (76) - I'd like to see this part as kk, 00:30:264 (73,74,75,76,77,78) - would work as a nice counterpart to 00:27:597 (66,67,68,69,70,71) - .
00:32:097 (79) - Would remove to shortend the combo lenght to be consistent with the counterpart 00:27:597 (66,67,68,69,70,71,72) - .
00:37:764 - 00:41:597 - We should have something easier here since it is a big difficulty spike, my idea was to do this:
https://derpovic.s-ul.eu/Nv9H1sbL.png Although it boosts the SR a bit, you should ignore that since SR is pretty garbage and not a good indicator for this case.
00:49:430 (19) - similar to 00:26:097 (62) - I'd remove this so to have a longer break, do the same for 00:50:764 (23) - and 00:52:097 (27) - too.
00:59:930 (54) - although the break wouldn't bre really longer I'd say to remove this note as well.
01:06:097 (74,76,77) - To make this part slightly easier I'd focus on the bgm only and remove 01:06:097 (74) - and 01:06:597 (76,77) - .
[Kantan]
nearly 3AM.. but whatever, the difficulty itself looks good. I may look closer to it next time.
Conclusion: Mapset itself is good, I actually like it. However, I wouldn't consider the map to be ready since Inner Oni has some structure problems, and Muzukashii/Futsuu should have some more checks after adding more rest/break times. I am not sure if you're willed to get more mods since this is the first mod after two months.