S1eth said: Considering the fact that it is white on the inside and that she always wears a school swimsuit, it is one.
The artist is obviously male and doesn't know that those school swimsuits are one-pieces and not two.
maybe we need a picture of her wearing it properly, so the artist we see the artist maybe intended to do a 2-piece suit (dunno the correct term lol). Im sure there are different versions for swimsuits, especially for a country which has a huge fetish for them.
Realize no-one's probably reading this anymore, but... this style of swimsuit is normally a two-piece. The top part overlaps with the bottom, covering part of the hips; this gives schoolgirl swimsuits the distinctive shape they have around the hips. There are, of course, variations.