コンパニオン/AF
Race Queen style costume from Alice Gear Aegis. There are other race queen outfits in the franchise's universe, but this is the only one featuring a leotard.
cf. https://wikiwiki.jp/alicegear/%E6%9C%8D%E8%A2%8B/%E3%82%B3%E3%83%B3%E3%83%91%E3%83%8B%E3%82%AA%E3%83%B3