宝石の国 [Hōseki no Kuni] is a 11-book series with 11 primary works first released in 2013 with contributions by Haruko Ichikawa, Cát Tường, and 市川春子.
2013 • 1 Reader • 196 pages • 5
2014 • 1 Reader • 196 pages • 4
2015 • 1 Reader • 196 pages • 4
2015 • 1 Reader • 196 pages • 5
2016 • 1 Reader • 196 pages • 5
2017 • 1 Reader • 196 pages • 5
2017 • 1 Reader • 196 pages • 5
2018 • 1 Reader • 196 pages • 5
2019 • 1 Reader • 196 pages • 5