A nemaki and a kind of yukata used as pajama or bathrobe after taking a bath. It is lightweight cotton and usually lined with a kind of gauze. It is sold with a same patterned belt.
In Japan it is often used as pajamas or nightgown, especially in hotels.
In general, there are 3 or 4 sizes: S, M, L, LL.
The women's nemakis often have floral motifs, while those for men are less salient geometric and non-Japanese men may prefer women's nemakis.