We know from her previous leaks when she was published as a sports reporter, as well as the release of her Yuna Kawase gravure that she's in her 40's, probably early 40's, but no-one can say for certain.
I don't think she is on any sort of drug( at least not anymore) I know for the longest, people have been hollering Ozempic. Thing is...if she was ever on it, she'd either (A) have to take it for the rest of her life and go broke cus they are not cheap or (B) learn to control her eating habits and get and keep a good workout routine. As glp1 are not fat burners...they are hunger suppressants. which is why it is important to fix eating habits before stopping. I think she just is maintaining her body. I think she is just lost a little too much and makes her look a bit odd.
The "official" birthdates for both Kaho Shibuya and for Yuna Kawase were created by her management agencies at that time; unless you've tracked down her birth certificate, you have no way of verifying her actual age. She's on record that the birthdate for Kaho Shibuya is incorrect; she's never spoken about her days as Yuna Kawase, for what should be obvious reasons.