This darling cutsew from the brand Honey Cinnamon is the absolute cutest for layering under JSKs! The cross-straps at the neck and ruffle detailing give it such a cute look, as do the puffy sleeves.
This is made from a soft, almost waffle-knit material that has a LOT of stretch, so it can accomodate a number of sizes!
Bust: 32-44 inches (could honestly probably go a bit bigger though)
Purchased second hand but only tried on by me; I couldn't find any flaws on it.