I dont get the system, but I can tell for sure it should be redisigned, FULL random - shitty practire. I did over 400 runs over the DarkLord = 1 girl unlock. What the fuck is that? Pointless, if witing a week of non-stop farming i didnt get 2-3 girls, would you expect me to farm 1 month per girls? Im fucking hate RANDOM.
Please guys, you can check yourself, there are 2 guys playing your game equal amount of time: 1st one got all of the girls within 2 weeks, 2nd on grinding for 3 monthes and have NOTHING - do you really belive that this system is FAIR enough?
You should go for a kind of bonus, each failled attemped gives you (for expample) + 0,1% of drop chance, so it means afrer 200 tries he would have a change on each fight ~20% so it would make it reasonble and within 300 attemps you would get a girl for SURE.