Yamada Asaemon Eizen was the 1st rank Asaemon in the Yamada clan.
After the shogun called for criminals to acquire the Elixir of Life from the dangerous island known as Kotaku, in exchange for a pardon for their past crimes, Eizen joined in the expedition team as one of the Yamada Asaemon monitors and was assigned to keep watch over the criminal, Rokurota.
