Arc 3Aizen and the River Campaign
Kōki’s missions with Butterfly Squad escalated into a battle against Sunagakure, while Aizen hunted targets and gathered secrets independently. Sunagakure identified Kōki as the force behind the attacks, and Kōki left seeking another way to obtain Tobirama Senju’s research.
- Kōki sealed Kurama Some’s corpse into a long-lasting Shadow Clone, which named itself Aizen and set out to gather records and techniques while Kōki asked Hiruzen Sarutobi for Tobirama Senju’s research.
- Aizen killed Mano Seiichiro in Kumogakure, then hunted Kawasaki Ya and took his corpse after defeating him with Genjutsu.
- Kōki joined Nara Yūsuke, Yamanaka Kenji, and Akimichi Tsuyoshi on missions against Sunagakure infiltrators, saving the squad from an explosive trap and helping defeat the enemy team.
- Kōki’s squad attacked a Sunagakure outpost, where Kōki fought through the defenders and destroyed their puppets before the team moved on to disrupt supply lines.
- Kōki and his teammates burned a Sunagakure supply convoy, then fought through an encirclement and escaped toward the Land of Fire.
- Chiyo linked Kōki’s Water Release and Taijutsu to the attacks on Sunagakure forces and ordered that he be killed if encountered.
- Kōki demanded more of Tobirama Senju’s research from Hiruzen Sarutobi, then considered seeking the records from Tsunade or Orochimaru.