Arc 12Rain, War, and Reunion
Koki helped Konoha survive attacks from rival villages before traveling to the Land of Rain, where he found Nagato, Yahiko, Konan, and the surviving Akatsuki in desperate straits. After Koki fed and cared for them, Nagato confronted his traumatic memories, and Yahiko persuaded him to go outside rather than suffer alone.
- Koki killed the blond ninja, then joined Minato and reinforcements in the battle against Yugito, helping capture her at the cost of a grave injury.
- While Koki recovered, the system revealed his Mangekyō Sharingan and a final mission in the Warring States period, and Orochimaru warned that his blindness might last for an uncertain time.
- Koki hired Kakuzu as his bodyguard and traveled amid rising wars between Konoha and other villages, then accepted Hiruzen Sarutobi’s mission to investigate the Land of Rain.
- Koki witnessed the Land of Rain’s suffering and helped Sachiko’s sick mother before Nagato led him to the wounded and starving Akatsuki survivors.
- Koki showed the survivors Jiraiya’s letter, provided them with clean water and food, and treated Yahiko’s wound while Hanzo of the Salamander let them remain in their cave.
- Nagato relived the murder of his parents and his childhood suffering, smashed his mirror, and injured himself before Yahiko brought him medicine from Koki and invited him for a walk.