KAWAJI won the great trust of OKUBO, who became Secretary of Interior after the resignation of Takamori SAIGO, and he took the responsible for spying on fuhei shizoku (former samurai with complaints) after the attempted assassination of Tomomi IWAKURA (the Incident of Kuichigai-mitsuke) and the War of SAGA.
西郷隆盛らの下野後は内務卿となった大久保利通から厚い信任を受け、岩倉具視の暗殺未遂事件（食違見付の変）、佐賀の乱などが起こると密偵を用いて不平士族の動向を探るなどの役目も果たした。