I have to google a LOT of shit when I work on this manga... not a single result for women's swimwear gear like what was in this chapter. They apparently exist for men, but everything I found about women's swimming agreed not to wear anything under your swimsuit, lol. My guess is tugeneko made it up because he thought it'd be funny for the no-panty girl, idkSo uh, what's the "supporter" even for? Just to prevent cameltoes?