E-ink screens are on the market from many years. They use less energy, and are quite flexible, so Triumph used them to make an innnovative bra that can change its color from white to black. Just activate the switch and BOOM, color change!
Enough with words, the video shows the action much better.
This is the “sisters” kit (姉妹 – Shimai) inspired from Frozen – where the elder one gets the 姉 (Ane, elder sister) and the younger gets the 妹 (Imouto, younger sister). When they’re nearby, BAM, the bra can change color.
This other video shows more: https://www.youtube.com/watch?v=voH1b5z9BCU
Anyways, it looks like the screen is not flexible enough for the shape, they separated it in two halves and it still looks too hard. (Maybe that’s why they chose skinny models?)
Fonte: Kyodo News