乱波

乱(らっ)波(ぱ) • (rappa) 

1. A spy. Especially, during the Warring States Period, a brigand recruited by a daimyō to work as a spy.
   • 1939, Eiji Yoshikawa, Taiko, Tokyo: Kodansha, published 1990:

     つまり、乱(らっ)波(ぱ)ですね。人(ひと)心(ごころ)を攪(こう)乱(らん)し、その機(き)に乗(じょう)じて、事(こと)を謀(はか)る

     Tsumari, rappa desu ne. Hitogokoro o kōran shi, sono ki ni jōjite, koto o hakaru

     In other words, we're hired spies, aren't we? We cause confusion, and devise a plan that takes advantage of that opportunity.

2. A ruffian.