This is the best idol game I've played - male and female idols included.
It's an actual raising sim, you just don't mindlessly click like enstars, you have to raise their skills in every area to get more fans and progress in the different producing programs, and the fact that you even have so many different producing gameplay is amazing. The producing phases can be quite long, but you can stop and pick it up again whenever. i really enjoy that they're longer because you feel more involved with your idols.
I usually focus on one or two characters in games, but in this one you do have to produce all of them to participate in the festivals, which I think is a good way to make you try every character and you don't get bored easily.
They do have a lot of paid gachas, but they also have a fully free one and the event cards are easy to get, so even as a free player, you don't feel like you're missing out.
Lastly, the character design is just so good!! It's what made me play it in the first place. I couldn't get into im@s for a long time because I didn't like the chara design very much so I couldn't find characters I like (even on M side), but in this one they're all so pretty and cute!
You don't even need to download this one as you can play on your browser, so definitely give it a try!!
The only bad point - it drains a lot od battery and makes my phone heat up pretty fast, so I usually play it on a tablet