Underwater Mecha Knee Socks

The new mecha [knee-high socks for use underwater] were designed and produced by Naoki, Mecha Designer on Gundam Build Fighters Try.

http://otakumode.com/news/540d4882ce9dc52032b65665/Underwater-Mecha-Knee-Socks!-Suichou-Niso-Plus-Book-Combining-Knee-High-Socks-Girls-Underwater-to-Release