noun
first volume; volume one
Used for the first volume in a two- or three-volume set; often contrasted with 下巻 (last volume) and 中巻 (middle volume).
この小説の上巻はとても面白かった。
The first volume of this novel was very interesting.
上巻だけ読んで、まだ下巻を買
I've only read the first volume and haven't bought the last volume yet.