Rumi is easy. Her low HP between phases, and the fact that she heals you every phase makes her easy. She doesn't heal you between every phase in boss rush though, but that's where Healing Staff comes in.
You know, you're supposed to use both Hammer and Ribbon in conjunction with each other and never stop attacking. That's the only way to gain better rank.
This game does have it's own version of Megalovania dude. There's this one boss who have an exclusive status called Mortality, it eliminates all sort of invincibility including from Bunny Amulet, and especially from taking damage. This means that you takes damage every frame if you stay in harm way.
[nsfw]http://ic.pics.livejournal.com/youreveryneetz/80171864/27497/27497_900.png[/nsfw]
NSFW because it's too brutal. Plz nerf.
99 Reflect return your damage back to yourself if your damage happen to surpass 99, which is easy not to do if you just use Healing Staff. There's a much stronger version of it that will kills you outright if your damage surpass 300 (300 Reflect). I once become too overconfident (And forgot about 99 Reflect) and inflict 3000+ damage to her, it completely massacres my HP.
So... Rabi Rabi Island is basically Gensokyo? With Noah as Yukari?
I like System Interior II, it's just a test of your platforming skills to the limit. It's BGM is one of my favorite, the best one is definitely Speicher Gallerie. My favorite part is where you must stay airborne as long as possible using combination of Double Jump, Air Dash, and Wall Jump.
Re: outrunning the bomb: Walking is awfully slow... there's other mobility options available.
Which brings me to my shilling of Bunny Strike. I think it's the only thing fast enough to outrun the bomb. Air Dash brings your acceleration to 0 at the end of it.
Noted!...Shame the three superboss rematches, to my knowledge, don't have such things, and one of them prevents you from using Ribbon so...Yikes.
One of these days I will get the Red Boost right. One of these days...
There's this one boss who spend 2/3 of her time airborne and stationary. Probably it's the correct time to use it? But then again, she's so hard you must use Healing Staff to survive.
Tips: Quick Load in-game = Select + B
Now it's time for my favorite character.
Hint: Use Bunny Amulet along with all your platforming skills in Library.