"4 rainbows per team" is a bit on an exaggeration for Kodaibana and Re: Sakura & Ume. People have done both with a single team (as in, five girls at fullspec) before, I had nine rainbows when I completed the third Kodaibana map.

I'm not entering Aqua Shadow again until I have another rainbow or two, though. That dodge-piercing ability kind of puts a damper on things, you really want some debuff and barrier rainbows for that map.