This makes me laugh so hard, for a number of reasons. One is the Aya yukkuri and that puzzled face she is giving the anon, as if to say "What... are... you?" Two is the artist's tendency to plop a yukkuri face on inanimate objects. Three is the awful anatomy, especially the way Aya is holding that wine glass.
Tag Check: why do we have a "drawing" tag? 99.9% of images on this site are drawn while the minority are 3D and real life photos. We only need tags for those.
You can, however, replace "drawing" with "colored_pencils" if you so choose.
Sketches in my opinion are just hand drawn pictures that are scanned in as opposed to ones done straight off photoshop or paint. It does't have to be a messy drawing.