Nice choice Ninja. Bunny Balloon-chan is really cool and she is a good Crit 5*.

I used my first SP stone for Winter Cosmos:

I planned to try her on the reissue gacha. Thanks to the stone, I can save more FG for a next gacha.
She is cute, she reminds me Shiro-chan and she has a nice ability set.

I haven't used the second one yet because I got EasterEvening Primrose just before the stones with saltickets. And there is no more 5* I really REALLY want and need. Most of the lasts girls I want are from 2015 (and I still have 3 2015 stones) and I will not use them anyway because I already have too much gold (I can't even use my new rainbows because there is no 5* I can or want to replace...).
I will keep it a bit. Maybe if there is a good 6* promotion or until I ran out of interesting girls to level up.