This addon is based on data information from CraftJapanizer (https://www.curseforge.com/wow/addons/craftjapanizer) and WoWJapanizer (https://www.curseforge.com/wow/addons/wowjapanizer) which has been imported into Tooltips Translator - Chinese (author: qqytqqyt, https://www.curseforge.com/wow/addons/tooltips-translator-chinese).
This addon adds Japanese text for spells, items, and also NPC/enemy nameplates if you use the addon Plater Nameplates (https://www.curseforge.com/wow/addons/plater-nameplates).