secret plan; secret strategy
A confidential plan or stratagem, often with a connotation of cleverness or cunning. Used in contexts like business, politics, or games.
He is devising a secret plan to compete against the rival company.
The shogi player faced the match hiding a secret strategy.
Compound of 秘 (secret) and 策 (plan, scheme). The reading ひさく is the standard on'yomi combination.