too expensive. we had deals which were cheaper and offered some extra draws and skill- and dressblooms. but this way it's easier for FKG devs. so they didn't had to think about a new gacha... "let us just selling the rainbows. they will buy it anyway"
Pretty sure Nutaku is just publisher though? Devs is DMM.
FKG ID
DMM ID: 561075604 (106/107)
IGN: Dusk
[Just a guy with bad self control and blow his gems for more salt and sodium chloride]