RQ: [HELP] Mushihimesama PS2 weird practice mode

[Hydeux]

Hi, as I'm still waiting for my Mushi HD, I've been playing a while on the Original mode of the PS2 port.
But things are unclear to me in the practice mode : you can select the rank you want to play (didn't even know there was a rank in Original !).
You got :
- No Miss
- Default
- Rank 1-10

First, I don't know what's harder : No Miss or Default ? I would say No Miss, but I'm not sure of that...
Then, what's the use of the third choice ?!? you can choose position 1 to 10, but for each one you have to play the game from the beginning, and I haven't notice any difference...

Would somebody know the answers ? (and be so kind as to give them to me !)
Thanks !

(edited thread title to fit with strategy section guidelines /nZ)

[BulletMagnet]

I don't know very many specifics about how rank works in Mushi, but I do know it's there: in Original you can definitely see the bullets getting faster as you get farther in. If memory serves difficulty is mostly determined by survival time: if this is true, then "No Miss" would actually be the toughest setting. Score probably also has something to do with it, but I couldn't get a whole lot more specific than that: someone else will have to take over from here.

[Hydeux]

Thanks for your answer anyway.

And talking about PS2 port of Mushihimesama, I've discovered a little funny thing this morning : during the loading times (some are massive !), you can mash your l1/l2/r1/r2 buttons and it will make Reco walk, reach the other side of the screen and fall asleep.
Quite useful, isn't it ?