Re:Zero (Full title: Re:Zero − Starting Life in Another World) is a ongoing light novel series written by Tappei Nagatsuki and illustrated by Shin'ichirō Ōtsuka. The series also has 2 popular anime seasons, with the second season still airing.
The Re:Zero - Art Works Re:BOX is a great looking boxset (with Emilia in the front and Rem at the back) that includes an art book and 2 light novel books compiling short side stories (obviously written in Japanese). The art book contains approximately 150 pages and is divided into several categories: illustrations based on the first 3 arcs (which is basically the first season of the anime), character designs and other (unreleased) art works.
Most of the illustrations are colored and in superb quality, especially the art works that cover 2 pages are so gorgeous. There are also a few in black and white, these are also of high quality, especially if you compare them with the light novels themselves.