Some density concerns throughout the set, as follows:
Kantan
00:05:777 (6,7,8,9,10,11,12,13,14,15) - I like the idea here, but without a substantial break beforehand this seems tricky for the difficulty level. You could either rework the start slightly to accomodate a 4/1 break by, for example, placing a 1/1 5-plet between 00:01:604 (1) - and 00:03:690 (3) - , or you could try a different, more linear rhythm to remove this issue.
00:12:038 (15,16,17,18,19) - the 3/4 over notes 16 and 17 should be followed by a 2/1 break, since this rhythm is considered complex for this level. Removing 00:13:604 (18) - would be an ideal fix for this if you want to keep this rhythm, if not you can move 00:12:951 (17) - on to the white tick and adjust colouring.
00:21:430 (29) - Remove this note to create a 4/1 break in order to comply with the ranking criteria.
00:22:473 (30,31,32,33,34,35,36,37,38) - same issue as 00:12:038 - , but if you want to keep this rhythm then removing 00:24:038 (33) - and 00:26:125 (37) - would be ideal.
Futsuu
00:03:690 (6,7,8,9,10,11,12,13,14,15) - This amount of 1/2 followed by 3/4 could be quite tricky at this level. Removing note 7 would resolve this issue without removing too much from the rhythms represented here, however a 2/1 break would be necessary afterwards, which can be fixed by removing 00:06:299 (13) - and 00:06:560 (14) - , placing a don at 00:06:821 - , and changing 00:07:082 (15) - to a kat. The colouring doesn't have to be as I mention, but that feels the most correct for following the drums.
00:17:777 (41) - and 00:26:125 (62) - Remove these notes to create 2/1 breaks in order to comply with the ranking criteria.
Muzukashii
00:01:604 (1,2,3,4,5,6,7,8,9,10,11,12) - the 1/4 2-plet followed by the 3-plet with no substantial break between may be a challenge for this difficulty level. Removing the note at 00:03:430 - would resolve this issue without removing too much from the rhythms represented here.
00:14:125 (45,46,47,48,49,50,51,52,53,54,55,56,57,58,59) - these 1/1 break timings are quite unconventional, and while they do follow the ranking criteria, I feel as if this section could be adjusting slightly to allow the breaks to rest at more conventional points of the songs. The first half of this would follow similarly to the rhythms at 00:18:299 (59,60,61,62,63,64,65) - , but with the inclusion of 2 notes at 00:14:386 - and 00:18:560 - . This would also involve removing 00:15:951 (51) - to create the desired break, and you could also add a note at 00:17:256 - for better flow. If this is slightly confusing feel free to shoot me a message and I can elaborate further on this.
00:24:560 (80,81,82,83) - Suggestion: I prefer following the sound of the saxophone here as it's the more prominent instrument in this part, so moving 00:24:821 (81) - to 00:24:821 (81) - would flow nicer.
00:27:951 (92,93,94,95,96,97,98,99,100,101) - Suggestion: You could make a slightly more interesting ending by removing 00:28:473 (94) - and adding a 1/4 3-plet of kats at 00:29:517 (99) - .
Oni
00:01:604 (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20) - Starting at this density here may be a bit much, removing 00:03:430 (10) - would resolve this issue.
One final suggestion: consider increasing the OD values for the Kantan and Futsuu by 1, to create a more linear trend between the difficulties.
Sorry for yapping, I hope this feedback is useful to you!
