I've noticed some of the under accessories are a bit inconsistant, i tried every one of them except the bath towl and here are the results:
dark robe turned into hoshido crown (sumeragi's mask)
bold swimsuit turned into a bath towel
seashell suit turned into love bracelet
toga of love had to be removed due to "missing dlc"
and finally, tropical suit turned into an emblem shield
strangely they all took up the under slot and thus could be stacked with other accessories on the arm/face slot unless removed (and could only be removed by equipping a bath towel in the case of love bracelet/hoshido crown/emblem shield, once removed it will act like the regular item and go back to its appropriate category: face for hoshido crown, and arm for emblem shield and love bracelet) I'm not sure if i would need a custom firmware or something in order to access the actual items but i just wanted to bring this to attention.
well if you need it for reference, i was using the NA version of the game