I'm looking for a specific manga about a girl who's mum makes her become an idol singer and her gender is unknown? And there's this one guy 'love interest' that finds out her identity.

I think her name started with an S but I'm not sure

There's also this one chapter where she has this card saying she's the main male characters fan or something.

Obsessed with reincarnation
....
Key to the Stars

Charisma Doll perhaps?

Be kind or get banned

Star Project Chiro?