After the shogun became impatient of the first team acquiring the Elixir of Life on Kotaku, Shugen and a second team were sent to acquire the elixir. Upon landing on the island and finding evidence of his Asaemon allies dead, Shugen ordered the team to eliminate the surviving criminals and any monsters they find on sight.
Shugen has chin-length hair with bangs that frame the sides of his face and slight hints of shadow below his eyes. He wears the standard attire of an Asaemon but wears a black robe and hakama instead of the standard white which matches his kataginu.
Shugen is very dignified and diligent in his duties as an Asaemon. Shugen cares greatly for his Yamada clansmen, having spent his years with them and being taught what they know. He greatly expressed his concern for their safety on the island and vowed to bring them back home no matter what the means were. Furthermore, Shugen has a tendency to become emotional whenever he thinks about his comrades. Even though the Yamada clan view women as inferior of becoming a executioner, Shugen is one of the rare few who do not believe in this belief as he vouched for Sagiri's qualifications in receiving a ranking and also did not think ill of Isuzu. It seems that the only member he has a low opinion on is Jikka who acts as his complete opposite and doesn't take it lightly when he does not conduct himself in a dignified manner. Nevertheless, Shugen refers to him properly as his senior. Among his clan members, Shugen shows the most concern for Eizen who was the one who took him in when he was young and promised to oversee his maturity as a Yamada Asaemon. After finding his corpse, Shugen broke down into tears and took the time to lay his soul to rest with a prayer.
Shugen greatly despises all criminals and truly believes that they are evil no matter who they are. At a young age, Shugen could not understand the Yamada clan's way of thinking when executing criminals and believed that they should all deserve a painful death. He believed that it was pointless to task the criminals from the vanguard party to retrieve the Elixir of Life and expressed his concern of the thought of one of the assigned criminals completing the mission and receiving the pardon, stating that it would leave him with nightmares. He also did not place his trust in the Iwa ninja and viewed them no better than criminals as well. Shugen's disdain towards criminals originated from the time his parents were killed by a murderer and sought revenge against the killer by executing them.
Shugen believes in order of all things in the world; the order in which those who abide by the law are to be protected while those who break them should be punish without mercy. As an executioner, Shugen has shown a great display of ruthlessness when performing his duties. A great example being when he executed the captured underlings of the Silver Serpent yakuza group in order for their boss to reveal the remaining members that were not arrested and execute them as well. However, despite completing the task he was given, Shugen did not feel that justice had truly been fulfilled and moved towards executing the entire families of each member, showing no mercy in killing men and women, young or old, to infants. Although he was merciless in his duties, Shugen showed what little sympathy he had prior to executing the boss, shedding tears in hoping that he, along with the rest he executed, become righteous in the afterlife. Shion noted that no matter how critical the situation was, Shugen would not stoop so low as to ally himself with criminals or allow any Asaemon to ally themselves with criminals as well, even going as so far to state that his arrival on the island only made matters worse rather than good. Isuzu also vouched for this when she explained to Sagiri that Shugen places this brand of justice above his own desires, which was proven true when he cut down Fuchi who protected Gantetsusai from his wrath despite the years they spent together as comrades. Despite this betrayal, Shugen still thought of Fuchi as a comrade and ordered the Iwagakure shinobi to help him if he was still alive as he made his way to Hōrai's floodgates.
After finding the corpse of his fallen mentor, Shugen unleashed his ruthless, cruel nature and developed a more vengeful attitude, shedding a single tear of blood and furiously declared that he would kill every living thing on the island. He also becomes more violent and sadistic as he slowly carved away at a Dōshi until he told him everything he needed to know about the island. As they continue to travel the island and find the death of two more Asaemon, Jikka stated that Shugen was acting more psychotic after resorting to using the whistle the Dōshi had earlier to summon the Mōnshin and carry them to Hōrai.
After his parents were murdered, a young Shugen was taken in by the Yamada clan and looked after by Yamada Asaemon Eizen. He then undergone training as an executioner and learned all he could from his clan members. He eventually earned his name as a Yamada Asaemon and was given the rank of second. Sometime ago, Shugen felt that Sagiri was qualified for a ranking and begged his superior to consider in giving her one.
During one of his duties as an executioner, Shugen executed the captured members of the Silver Serpent yakuza group in order for their boss to reveal the remaining members hidden within the Castle Town. After successfully executing all 20 members of the group, Shugen moved towards executing the families of each member with the shogun present and the boss watching in horror moments before being executed. This event caused Shugen to have an infamous reputation but also caught the approval of the shogun who rewarded him with a sword named Fuributsu Kaneki and ceremonial clothing.
Lord Tensen Arc
- Main article: Lord Tensen Arc
Shugen sits next to Yamada Asaemon Jikka as he explains to the officials how he managed to return from the island. After angering them, Shugen apologies for Jikka's behavior. They overlook this incident and explains to them the next course of action written in the shogun's message, which is to send out another team of Asaemon to the island. Once they were done discussing matters, Shugen scolds Jikka's behavior but is met with disrespect by the senior Asaemon, causing him to become furious and speaks bluntly that he can not tolerate his attitude. After Jikka apologies, he wonders if there were any more criminals to send. Shugen informs him that the shogun has hired shinobi from Iwagakure instead of criminals and says that he will also be joining the next team as ordered by their leader, Yamada Asaemon Kichiji. He then sheds a tear after realizing that Eizen has failed to report back to him and becomes worried of his other fellow Asaemon members. A worker then comes up to Jikka asking what they should do with the giant monster head he had killed and brought back. Shugen gets close to the monster's head but the worker warns him that it may still be alive. However, Shugen says that the monster was dead after sensing no waves of life force. He then meets up with two additional allies and tells them that the four of them shall make preparations to depart to the island.
After departing the next day, Shugen thinks that Aoki is feeling uncomfortable with the ninjas presence and informs him that he can correct this. Aoki then becomes concerned with Kiyomaru and Isuzu being unranked Asaemon and wonders if they where capable of handling the mission. Shugen tells Aoki that despite not having a ranking they are skilled enough to handle themselves while also including Jikka, saying that he was adequate and declares that they will be determined to help his clansmen on the island. He then watches as one of the ninjas kills himself after being given the order by Kiyomaru to prove his loyalty and is approached by Kiyomaru asking if they can truly trust them. Shugen tells him that he never trust them to begin with and views them no better than criminals. He then expresses his resolve to kill the criminals on the island so that his clan members can return home. However, after being asked if they were already dead, Shugen becomes angry at the thought and tears up hoping that they are safe.
The group then finally arrives on the island. After landing, Shugen encounters a group of Sōshin and attacks them barehanded. Once he quickly dealt with them onster, Isuzu and Kiyomaru come to his aid but Shugen reassures them that as their senior, he will take on the responsibility of taking care of lesser matters like fighting the monsters. Jikka becomes pleads to hear this but Shugen reminds him that he is his senior. He then shockingly approaches the corpse of Yamada Asaemon Eizen and breaks down into tears.
Before he could agree to go any further on their journey, Shugen says a prayer to lay his former masters soul to rest. While praying, the group fight off a horde of Mōnshin commanded by a Dōshi to attack them. After he finishes his prayer, Shugen cuts the leg off a Mōnshin that attempted to attack him and uses its shakujō to chip away continuously at his blade. He then declares in anger that he will exact his revenge by killing every living thing on the island.
After quickly defeating the Dōshi, Shugen carves away at him until he answers his questions about the island. Jikka tries to reason with him by saying that they should return home, however, Shugen angrily scolds Jikka, saying that under no circumstances are they allowed to return to the mainland. After being calmed down by Isuzu, Shugen apologizes to Jikka but demands that the Dōshi provide him with information he needed. One of the ninja then comes up to Shugen suggesting that the ninja handle this matter since they specialize in interrogation and torture.
- Main article: Hōrai Arc
While traveling to Hōrai, Shugen becomes furious after the ninja reveals to him evidence of Tensa's and Genji's deaths. Shugen then decides to use the Horse Flute used by the Dōshi to call upon the Mōnshin. Once the Mōnshin were summoned, Shugen orders them to quickly transport him and the Asaemon to Hōrai.
Upon arriving in Hōrai, the Mōnshin breach the walls of the palace, allowing Shugen's team to enter. Shugen commands the ninja to confront and eliminate the convicts but spare the Yamada Asaemon. An army of Dōshi charges to attack the intruders but are all taken down by Shugen who warns the others that Dōshi's tandens are their weakness.
Shortly after, Shugen finds Yamada Asaemon Fuchi and demands an explanation from him as to why his criminal, Tamiya Gantetsusai, hands are untied. He then senses Gantetsusai's "blood lust" and silences him while he hears Fuchi's reason, who explains that the Yamada Asaemon had no other choice but to ally with criminals to survive the dangers of the island. Shugen accepts this fact and says that he no longer has to cooperate with Gantetsusai since he is here and ask that he execute him before joining his side, however, Fuchi refuses, saying that the time for crime and punishment will have to come later after they escape the island. After noticing how the missing tsuba on his sword was used as Gantetsusai's eyepatch, Shugen becomes shocked and angry seeing as how Fuchi mistreated his Asaemon soul. Shugen then clashes swords with Gantetsusai after he insults the Yamada clan. Shugen loses his footing but regains it after imitating Kishō and blocks Gantetsusai's next attack. He then begins to tell Gantetsusai about the memories he had with Yamada Asaemon Genji and releases the same strength Genji possessed to push Gantetsusai back. Recalling Gantetsusai's insult earlier, Shugen challenges him and states that he will use the power of all the Yamada Asaemons.
Shugen gains the upper hand in his fight with Gantetsusai by using the skills of Genji and Kishō with his swordplay. He then prepares to bring his sword down on the criminal but is stopped by Fuchi who tells him that despite Gantetsusai being a criminal he is not "evil" as he makes him out to be and also says that he does not wish to see more people die. Shugen ceases the assault on his blade and sees that Fuchi's caring side for others has not changed since the day they met. However, Shugen forces himself to cut Fuchi, saying that he wields his sword for the sake of the world. Gantetsusai tells Shugen that he is insane for cutting down one of his comrades. Shugen replies that what he did was determination and says that he is prepared to condemn him.
Abilities and Powers
Shugen is viewed by his peers as being the strongest Asaemon in the Yamada clan. Being the second ranked Asaemon, Shugen's suitability for becoming the next head of the clan rivals that of Eizen. Unlike the first group of Asaemon that were dispatch to the island, Shugen was one of the three that were chosen to join the second team based on pure ability alone. After arriving on the island, Shugen was capable of single handedly defeat a group of Sōshin without the use of his sword and easily cut down a Mōnshin with no signs of worrying. He was also able to defeat a Dōshi, students of Lord Tensen who are well-versed at using Tao than any human.
Shugen possesses impressive physical strength. He was able to break the leg of a large Sōshin and effortlessly lift its arms when it was trying to hold on to him. Combined with his knowledge of anatomy and his ability to sense Tao, Shugen was able to fight barehanded against a group of Sōshin and easily defeat them without a single scratch. Using his copying ability, Shugen can further increase his strength to match that of Yamada Asaemon Genji's, which was capable enough to overpower the likes of Gantetsusai.
Having spent his time carefully analyzing the ranked Yamada Asaemons personalities, strengths, and weaknesses, Shugen became able to copy their unique abilities as if his opponent is actually fighting the ranked Asaemon he chooses to emulate. By switching in and out of each skill he uses, Shugen's opponents become overwhelmed as if they are actually fighting more than one Yamada Asaemon. In addition, not only can Shugen use their talents to the fullest but he can also compensate for any weaknesses they may have by applying his own skill.
Yamada Asaemon Genji
Shugen is able to replicate Yamada Asaemon Genji's monstrous wrist strength in his swordsmanship. In his fight against Gantetsusai, Shugen was able to beat him in a feat of strength when they clashed, causing him to be pushed back a good distance. By adding fluidity with this ability, Shugen's swordplay is seen as an improvement to Genji's.
Yamada Asaemon Kishō
Shugen is able to replicate Yamada Asaemon Kishō's calm mentality to foresee incoming attacks as if he has saw a moment into the future, allowing him to avoid them and deliver a counterattack.
Yamada Asaemon Senta
Shugen is able to replicate Yamada Asaemon Senta's swordsmanship where he extends his arm to perform thrusting and cutting attacks. Shugen used this ability to fight at mid-range from the monsters created by the Zhu Jin-fused Banko to avoid being turned into flowers. By adding twisting force behind his attacks to make them more destructive, Shugen's swordplay is seen as an improvement to Senta's.
- Further information: Tameshi Ittō-ryū
Shugen is known to have great skill and knowledge in swordsmanship than any other member in the Yamada clan. As an Asaemon, Shugen is capable of decapitating his victims with a single cut of his sword. After chipping away at his blade, Shugen is able to execute cuts modeled after the execution method known as Sawing (鋸引き Nokogiribiki?), where he carves away at his opponent if they refuse to answer his questions. During the raid in Hōrai, Shugen gracefully beheaded every Dōshi while they were riding on horses. By applying his mimicry of every skill of the ranked Yamada Asaemons to his swordsmanship, Shugen was able to best Gantetsusai, an incredibly strong and highly experienced master in swordsmanship, and bring him to his knees.
- Tameshi Ittō-ryū: Autumn Shower — Kishō Version (試一刀流村時雨 期聖追悼 Tameshi Ittō-ryū: Mura Shigure — Kishō Bājon?, Literally meaning: One Sword Style Test Cutting: Autumn Shower — Kishō Version): Shugen uses the Tameshi Ittō-ryū: Autumn Shower combined with the calm mentality of Kishō's to overwhelm his opponent. This is called Ittō-ryū School: Harvest Shower Kisho Style in the Viz Manga.
- Tameshi Ittō-ryū Gaiden: Excellent Swift Thrust — Senta Version (試一刀流外伝 俊迅の突き 仙汰追悼 Tameshi Ittō-ryū Gaiden: Shunjin no Tsuki — Senta Bājon?): Shugen uses Senta's swordsmanship to rapidly pierce his opponent from a distance with destructive power. This is called Ittō-ryū School Gaiden: Swift Thrust — Senta Style in the Viz Manga.
- Tameshi Ittō-ryū: Helmet Drop — Genji Version (試一刀流兜落 源嗣追悼 Tameshi Ittō-ryū: Kabutōchi — Genji Bājon?, Literally meaning: One Sword Style Test Cutting: Helmet Drop — Genji Version): Shugen uses the imitated strength of Genji's to apply force to a single swing of his sword. This is called Ittō-ryū School: Helm Divest Genji Style in the Viz Manga.
- Tameshi Ittō-ryū: Helmet Splitter — Genji Version (試一刀流 兜割 源嗣追悼 Tameshi Ittō-ryū: Kabutowari — Genji Bājon?, Literally meaning: One Sword Style Test Cutting: Helmet Splitter — Genji Version): Shugen uses the imitated wrist strength of Genji's to apply a huge amount of force to his sword when clashed with another, causing his opponent to fall forward. This is called Ittō-ryū School: Helmsplitter Genji Style in the Viz Manga.
- Further information: Tao
Shugen is capable of sensing Tao, which he learned from Shion. In combat, Shugen is able to target the weak areas of his opponents Tao and deal lethal damage.
Shugen possesses knowledge taught to him by a few of his fellow clansmen, such as Fuchi's understanding of anatomy and Shion's ability to perceive Tao. These two studies combined allows Shugen to easily defeat his opponents in a fight even without the use of his sword.
Having impressed the shogun, Shugen was given the named blade, Fuributsu Kaneki. After arriving on Kotaku, Shugen acquired the Horse Flute that was previously owned by a Dōshi he defeated. He later used it to call out the Mōnshin from their nest to have them carry him and the Asaemon to Hōrai.
- Shugen ranked 15th in the manga's 1st Character Popularity Poll.
- In chapter 2, a silhouette of a person bearing resemblance to Shugen can be seen in Sagiri's flashback.
- Up until Chapter 56, Shugen initially wore the standard white robe of an Asaemon but was later redesigned to wearing a black robe. This suggests that this adds to Shugen's hatred towards criminals since the white robe is meant to symbolize the Yamada Asaemon's sorrow for criminals as they execute them.
- Shugen suffers from a condition known as haemolacria.