Yamamoto Kansuke

Yamamoto Kansuke is a minor antagonist in the anime In Another World With My Smartphone (specifically appearing in the Eashen arc). He is an evil necromancer and cunning strategist who initially serves as an advisor (and right-hand man) to the daimyō Takeda Shingen in the Divine Nation of Eashen.

Driven by corruption from a powerful artifact called the "Jewel/Immortality Gem" (embedded in his eye), he betrays and murders Shingen, then manipulates events to incite a war between the Takeda and Tokugawa clans. He raises and controls an army of undead (including using Shingen's reanimated corpse as a puppet) in his scheme for power and domination. Voiced by Kenjiro Tsuda (Japanese) and David Trosko (English), Kansuke is ultimately defeated by the protagonist Touya Mochizuki, who removes and destroys the immortality gem, ending his influence and undead forces.