My bits of feedback.

I think the stamina costs in stories is fine, and I think the rate at which stamina regens is fine, but I think the stamina cap is way too low. This game would work well as something you check in on 2-3 times a day and advance a few frames, but my stamina currently fills up in under 3 hours and is expended getting through just 3 lines of the same frame. Same deal with battle points and harem earnings. For a game that requires so little interaction most of the time, it requires far too much attention, doing the same simple tasks: collect earnings, advance 1-2 stages in the story, fight dark lord twice, come back an hour later and do it again. The pacing wouldn't change by increasing these pools and people wouldn't be any less motivated to spend money refilling to speed things up, you'd just get slightly less traffic.

The koban cost for collecting earnings, while completely silly and I don't imagine anyone using, is fine with me. What's not fine is that it's not made clear that it's costing 2 kobans instead of adding 2. At first I thought it was great that the girls slowly generate kobans as well as money, it made the koban prices for other things not seem so ridiculous, and I spent like 12 kobans collecting earnings before realizing it was a cost not a gain. It feels like this is a trap to intentionally make people spend their starting kobans before being able to roll the gatcha, and it worked on me, congrats.

Other than that I actually enjoy the art and story and while I'm still only late in the Gems Kingdom and have 0/3 girls from Dark Lord, I'm already looking forward to see what new content is added. Hopefully a bunch more girls and other ways to earn them, like some easier to get early options for those of us with terrible luck.