Eiji was an anthropomorphic cat and a Neko Ninja.
Eiji was assigned by Shingen to spy on Lord Tamakuro and his operations. He slew a guard who would have spotted Tomoe Ame when she was hiding in the fortress. He then returned to the secret hideout of the Neko ninja to report to Shingen. His report, that Lord Tamakuro was already preparing to move his forces out, necessitated the attack upon the castle by the Neko ninja, joined by Miyamoto Usagi and his allies.