This set is published in the bunkoban format, A6 in size (148mm x 105mm, a bit less than 6" x 4") so they are the smallest volumes in my collection. The first 4 volumes are FR (two volumes per original LOTR Book, 1 and 2), the next three are TT (two volumes for Book 3 and one volume for Book 4), and the last two are RK (one volume per Book, 5 and 6).
指輪物語 (Japanese A), purchased on-line from goodlifeyourlife, Osaka on ebay in 2021 (paperback)
Tolkien, J.R.R. 指輪物語. Translated by Teiji Seta and Akiko Tanaka. Vol. 1, 旅の仲間 上1. Hyoronsha, 2002. ISBN: 4-566-02362-1
———. 指輪物語. Translated by Teiji Seta and Akiko Tanaka. Vol. 2, 旅の仲間 上2. Hyoronsha, 2002. ISBN: 4-566-02363-X
———. 指輪物語. Translated by Teiji Seta and Akiko Tanaka. Vol. 3, 旅の仲間 下1. Hyoronsha, 2002. ISBN: 4-566-02364-8
———. 指輪物語. Translated by Teiji Seta and Akiko Tanaka. Vol. 4, 旅の仲間 下2. Hyoronsha, 2002. ISBN: 4-566-02365-6
———. 指輪物語. Translated by Teiji Seta and Akiko Tanaka. Vol. 5, 二つの塔 上1. Hyoronsha, 2002. ISBN: 4-566-02366-4
———. 指輪物語. Translated by Teiji Seta and Akiko Tanaka. Vol. 6, 二つの塔 上2. Hyoronsha, 2002. ISBN: 4-566-02367-2
———. 指輪物語. Translated by Teiji Seta and Akiko Tanaka. Vol. 7, 二つの塔 下. Hyoronsha, 2002. ISBN: 4-566-02368-0
———. 指輪物語. Translated by Teiji Seta and Akiko Tanaka. Vol. 8, 王の帰還 上. Hyoronsha, 2002. ISBN: 4-566-02369-9
———. 指輪物語. Translated by Teiji Seta and Akiko Tanaka. Vol. 9, 王の帰還 下. Hyoronsha, 2002. ISBN: 4-566-02370-2