Genkaku was a popular war hero during the war between the Highland Army and the City-State of Jowston in 428. Genkaku quickly rose to prominence in the State Army after a unit he commanded raided a Highland supply tent, buying the City-State time to recover. Genkaku was also instrumental in helping the Winged Horde move from Tinto Principality to Two River City after their lands were seized for strip-mining.
During the war, Genkaku encountered his friend Han Cunningham, who came from the same village as Genkaku, as an enemy commander. The two did not let the war effect their friendship and would drink together in the middle of both camps; gradually, the two came to realize how stupid the war was. At some point, Genkaku came into the possession of the Bright Shield Rune while his friend Han received the Black Sword Rune.
The two drew up plans for a peace treaty that pleased nearly everyone, save the mayor of Muse City, Darell. Darell stubbornly refused to give the border town of Kyaro to the Highland Kingdom. With all sides tired of the war, Highland King Agares Blight came up with an idea for deciding a victor - the two nations would each send forth a champion in a duel. Darrell agreed to this, and the two heads of state chose Genkaku and Han as their champions.
During the duel, Genkaku refused to raise his sword to battle Han; as time passed, people became angry with Genkaku for refusing to fight. Eventually, Han knocked Genkaku's blade out of his hand and was declared the victor. Genkaku was called a traitor and exiled by Darell. It was not until years later that the reason Genkaku refused to fight became known. Darell had coated Genkaku's sword with poison; even if he had won, Darrell would have exiled him anyway for murdering Han. At some point, he and Han sealed their runes in a cave in Toto Village.
After leaving the City-State of Jowston, Genkaku retired in the Highland Kingdom, where he opened a dojo and adopted two orphans, the hero and Nanami. Though not related by blood, the three happily bonded as a family. He eventually passed away in SY 458.
The mystery as to why Genkaku refused to duel Han remained a secret for a long time but eventually emerged. After his death, Anabelle] lamented that Muse could not atone for their sins against Genkaku. His adopted son would one day come to possess the Bright Shield Rune and become the leader of the New State Army, a role he was chosen for due in part to his inherited reputation as Genkaku's son.
- Genso Suikoden Kiwami Encyclopedia, page 150