六りく韜とう三さん略りゃく

Meanings

The Six Secret Teachings and The Three Strategies of Huang Shigong

Refers specifically to two ancient Chinese military classics: 六韜 (Rikutō) and 三略 (Sanryaku). Used in historical or literary contexts.

彼かれは六りく韜とう三さん略りゃくを熟じゅく読どくし、兵へい法ほうの奥おう義ぎを極きわめた。
He thoroughly read The Six Secret Teachings and The Three Strategies and mastered the secrets of military strategy.

noun

secrets of the art of war; mysteries of strategy

yojijukugo (four-character idiom)

Figurative extension: refers to profound knowledge or secrets of military tactics, or more broadly any arcane expertise. Often used in the phrase 六韜三略を極める.

彼かれは商しょう売ばいの六りく韜とう三さん略りゃくを心こころ得えている。
He knows all the secrets of the trade.