>>530996963
Leon has it worse where all info about her (even birthday and height) is unknown. Just don't think much about it. Like Kuroi has his three sizes known but none of the SideM does.

As far as "lore" goes, Manaka is the flattest while Letora is said to be the biggest. Although, the recent goods depicting them in their new jersery avatar has both Cosmo and Letora seemingly around the same size (Cosmo's taller so it might just be the same surface area but Letora has better volume).
https://idolmaster-official.jp/news/01_15890