You need coins to upgrade and evolve your units, along with the materials.

Originally Posted by hypo

You need coins to upgrade and evolve your units, along with the materials.

Thank you very much, you're a life saver!!

You will find yourself using MANY MANY coins over the course of the game. Evolving 5* girls is 150k coins the first time from memory and 6* are 250k then it's extra for each Manyu you feed them and the higher the girls level the more it costs. I have found from experience that 10,000,000 coins does not last long when you start a serious girl / equipment upgrade cycle and more often than not i'm below 1 mill coins at all times these days.

Originally Posted by Zandel

You will find yourself using MANY MANY coins over the course of the game. Evolving 5* girls is 150k coins the first time from memory and 6* are 250k then it's extra for each Manyu you feed them and the higher the girls level the more it costs. I have found from experience that 10,000,000 coins does not last long when you start a serious girl / equipment upgrade cycle and more often than not i'm below 1 mill coins at all times these days.

considering i'm packing 19 of the 6* girls in the game, i'm burning through coins faster than I burn through stamina...

i tend to find myself spamming flower gems at stam refills a ton just to get the coins... especially since I'm almost never doing the flower gem gacha anyway (unless they have a good step up or something...)

if it wasn't for the 50% potions being added as well, i'd likely would have drained storyline of all it's flower gems by now (i got them all up to chapter 24 though)

they are EXPENSIVE to build up, especially the Bloomable ones... but my god does it feel worth it when you get them to lv70/80 (and maxed out on ampy increases like my Lycoris)