Is there some reliable way of farming sake and cheap sake if one would want to evolve all 3* and 4* for sake of total war and h-scenes?

Cheap sake and sake drops here and there but so slow it takes me ages to evolve a single 4* or 3*.

25 stamina evolution mats map and all other maps give me so much mirrors and pure sake I actually wish that instead of those retarded exchange rates from cheaper material to better one (like 100 cheap sake to 1 sake) they had ones that let you change better mats to worse (even if it was 1/10 of actual rates in another direction).