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, Rokurōta.
Eizen had long spiky red hair and wears a large eyepatch that covered his left eye. He wore a dark haori underneath the standard attire of a Asaemon, which is a white robe with a bell tied to the left collar and a hakama held together by a waist-cord.
When he was younger, Eizen's hair was much shorter and wore a different eyepatch at the time.
Eizen had great pride for the Yamada clan and believed that no task was impossible for them when it came to executing people, such as his assigned criminal Rokurōta. As an executioner, Eizen knew that defiling the execution grounds by trying to bring pain to the condemned with his blade would defile the magistrate and followed the Yamada clan's ideal way of ending lives by cutting their victims with no pain or emotion, a concept which he tried to impart to a young Shugen. To this extent, he found it atrocious at how Gabimaru dealt with the criminals in the death match. Eizen is also kind and caring as he promised to look after Shugen when he was young, which brought a great influence to him in the present. Like his fellow clan members, Eizen believed that women in the Yamada clan should not follow the path of a samurai and was antagonistic when Sagiri took the shogun's mission.
Eizen, along with other members of the Yamada clan, stand on guard as the gathered criminals are told in detail about the mission to capture the Elixir of Life for the shogun. When one of them declined the mission, Eizen comes in to cut off his head since refusal of the mission was not an option. After the criminals were told to start a massacre in order to lower the number of participants, Eizen tries to discourage Sagiri from taking on the mission and bluntly stated that he disapproves of her being an Asaemon since she is a female. After the killing ended, Eizen got assigned to watch over Rokurōta and departed to the island.
As Rokurōta was being transported, the helping staff was wondering if he was as dangerous as the villagers said and worried about him waking up. Eizen assured them to not worry since he stated that the Asaemons were well suited for jobs such as this. After arriving, Rokurōta awakens from his sleep and was beginning to feel hungry. Seeing Rokurōta about to attack, Eizen tries to intercept it but fails and is ultimately crushed by Rokurōta's hand.
Eizen had a profound influence on Shugen as he was the one person the young man looked up to the most. Before leaving to Kotaku, Eizen promised Shugen that he would report back on the second day, causing him to become suspicious of his time on the island after three days had passed and cried in his absence. Shugen later went on to make it his goal of having Eizen and the other Asaemons return home in one piece after being order by the shogun to journey off to the island with a second team. After arriving on the island, Shugen becomes devastated after finding Eizen's corpse and took the time to lay his soul to rest despite the fact that his team was being under attack by Mōnshin. Eizen's death went on to impact Shugen on his mission as he vowed to kill all monsters and criminals on the island to avenge his fallen master.
Abilities and Powers
Eizen was the strongest Asaemon in the Yamada clan and was the most likely candidate to become the next suitable head of the clan. Like every Asaemon, he had the capabilities of decapitating a person with a single cut of his sword.
As an executioner, Eizen carried his own katana.
- Eizen ranked 17th place in the manga 1st Character Popularity Poll.