noun, noun or participle which takes 'suru', intransitive verb
betraying one's lord and going over to the enemy
Historical term for a samurai's act of turning against his lord to join the opposing side. Often used in the context of the Sengoku period.
戦国時代には、返り忠をする武将も少なくなかった。
During the Warring States period, there were quite a few warlords who betrayed their lord and went over to the enemy.
裏切り is the general modern term for betrayal or treachery, while 返り忠 is a specific historical term for a samurai's betrayal of his lord to join the enemy.
Compound of 返り (kaeri, 'returning') + 忠 (chū, 'loyalty'), literally 'returning loyalty', implying a reversal of allegiance. The exact historical derivation is uncertain.