A few suggestions and some feedback:
- I think it would be interesting if idols came directly to you more often if they felt unhappy or bothered. Maybe they want less work, maybe they want a raise, maybe they don't feel like practicing anymore, or maybe they don't like one of the group's policies. It'd be a good way to know what your idols are thinking. I just had an idol graduate less than a year after joining the group, at the age of 18, and maybe things could've gone differently if she had told me she was unhappy about her salary.
- 'Unfair' difficulty didn't seem to do anything. I actually had an even easier time making money this time, and didn't even have to get a loan from Fujimoto. Within the 1st in-game year, I was already sitting on tons of millions of yen (thanks to photoshoots and negotiations at first, then a few successful singles). Didn't even need to build a cafe to thrive. Other than saying "Nerf everything, make us suffer, we like pain, misery and bankruptcy", I'd suggest specifically slowing down the rate at which your staff levels up their skills (in order to force players to spend more money hiring new staff members if they wanna grow faster), or maybe even cap their skill development. For example: if the player hires a 'Beginner' manager with 2* contract skills, that manager can only develop their contract skills up to 5*. The player will, then, be forced to hire a better manager if they wanna get better contracts, and will either have to fire the 'Beginner' level manager, or keep paying her salary. And, speaking of staff salaries, they should be higher in the 'Unfair' difficulty, since they're not dynamic like the idols'. Just to make things more fun :)