Stole my friend's laptop to play this for a few hours before she booted me off of it. Completely obsessed.
1. Birthdays so I know when my idol becomes a hag starts getting too old.
2. Merch (hand fans, lightsticks, towels, decorative slogans, sticker sets) would be kind of cool. (You can limit this to concerts if you want. I know the focus is more on Jpop than Kpop.) Also fan accounts of any theatre/concert/handshake interactions.
3. This is probably being worked on but being able to manage staff salaries. Mainly for the dance/vocal instructors.
4. Being able to manually put idols on rest (mainly for stamina purposes.) Alternative would be to manually put idols in the break room or send them individually to the spa.
5. Another thing probably being worked on but being able to see what the girls post to SNS. I wanna know what my meme queen does, she probably flames people in the replies.
EDIT: 6. Pop-up calendar you can click on so you know when each deal is due, when loans are due, etc.
I've been into idols and idol culture for about 10 years and I think it's safe to say you've done a great job with this game so far. Keep it up!