I 〔仮名文字の〕the Japanese alphabet [syllabary]
arrange names in Japanese alphabetic [syllabic] order
II 〔初歩〕the basics; the rudiments; the ABC(s) ((of))
learn to play golf, starting from the basics
He doesn't 「have even a rudimentary knowledge of [know even the first thing about] nuclear weapons.
いろはガルタ｜iroha cards; a pack of cards, each of which is printed with one proverb beginning with a different letter of the Japanese alphabet; the iroha card game (for children)