Due to the requirement that official government documents make use of only jōyō kanji and their readings, several rare characters are also included by dint of being a part of the Constitution of Japan, which was being written at the same time the original 1,850-character tōyō kanji list was compiled.
Resmî hükûmet belgelerinin sadece jōyō kanji ve okumalarının kullanılma zorunluluğu nedeniyle, bazı nadir karakterler de Japonya Anayasası'nın bir parçası olmakla kalmaz, aynı zamanda yazılmış olan orijinal 1,850 karakterli tōyō kanji listesi derlenmiştir.