Kouha Kannei is a student of Nanyo Academy, a fighter who carries the soul of the ancient warrior Gan Ning. Physically, he is identifiable by his short brown hair and his choice of attire, typically an orange hoodie; he is almost always seen carrying his signature twin tonfa weapons. Despite his aggressive role in the story, his original nature was notably gentle. Before the events of the series, Kannei was a kind individual who genuinely enjoyed the spirit of fighting but was fundamentally unable to take another person's life. This peaceful disposition was violently shattered when he was manipulated into assassinating Enjutsu, the leader of his own school, Nanyo Academy. The psychological trauma of being forced to commit such an act drove him completely insane, warping him into a violent and unpredictable fighter.

Throughout the first anime series, Kannei serves as a primary antagonist and a tragic instrument of another character's schemes. He is given an imperial order to eliminate the protagonist, Hakufu Sonsaku, whom the leadership of Nanyo views as a dangerous threat. In his initial confrontations, Kannei demonstrates combat prowess far superior to Hakufu's, overwhelming her with raw speed and power. However, these fights are repeatedly interrupted, first by the intervention of the powerful fighter Shimei Ryomou, who subdues him with his own weapon, and later by the emergence of Hakufu's own hidden strength, allowing her to defeat him in a direct rematch. His motivations are largely stripped of free will; he operates under the belief that he is following the direct orders of Enjutsu. In reality, he is a puppet of Genpou Saji, the master strategist of Nanyo who orchestrated the murder of Enjutsu and uses a brainwashed Kannei as a tool to further his plans, including an attempt to unleash a destructive dragon spirit within Hakufu.

Kannei's key relationships are defined by this manipulation and his role as an enforcer. He is a member of the Big Four, the elite ruling fighters of Nanyo Academy, standing alongside figures like Gakushuu and Ryomou. His interactions with Hakufu's protector, Koukin Shuuyu, are marked by brutal hostility, as Kannei severely injures Koukin by breaking his arm during one of their battles. While his position suggests loyalty, his actions are ultimately a product of Saji's control, making him more of a broken weapon than a true adherent to the school's cause.

The character's development is a tragic downward spiral. He begins as a kind-hearted person corrupted by a violent act forced upon him. His descent into madness is complete by the conclusion of his active role, and by the events of the second anime series, Ikkitousen: Dragon Destiny, Kannei is no longer present as a combatant. It is stated that he had been confined to a mental institution, having never recovered from the insanity inflicted upon him by Saji's machinations. As a fighter, his notable abilities lie in his exceptional physical skill and ferocity, particularly his proficiency with the tonfa, which allows him to overwhelm many opponents in close combat before his own fractured psyche leads to his downfall.