Arai Zenko

Lord Arai Zenko (formerly Muto Zenko) is a former member of the Tribe, the last head of the Arai Clan, and one of the main antagonists of the Harsh Cry of the Heron. The illegitimate son of Lord Arai Daiichi and his Tribe mistress, Muto Shizuka, he is initially raised in his father's household until the birth of Daiichi's legitimate son causes Shizuka to bring him and his younger brother Taku to the Tribe, for their own safety. Despite Daiichi's rejection of him, Shizuka and Taku, Zenko continues to idolize and emulate his father and the warrior caste, even as he is indoctrinated in the ways of the Tribe.

During the Otori Civil War, the death of Daiichi's heir from illness causes him to change his attitude towards Zenko and Taku; however, not long afterwards, most of the Tribe joins Otori Takeo's faction. As a gesture of loyalty, Shizuka gifts her sons to Takeo as hostages, which he keeps secret from Daiichi after making a truce with him. Zenko and Taku both assist Takeo in the Battle of Hagi, but shortly afterwards, Daiichi betrays Takeo and prepares to storm the city. Takeo reveals that he holds Daiichi's sons, threatening to kill Zenko unless the Arai stand down; though shocked, Daiichi calls Takeo's bluff, knowing he is very reluctant to harm children. However, his hesitation allows Takeo's ally Terada Fumio to kill Daiichi with a firearm; simultaneously, an earthquake destroys much of the Arai army, leaving Takeo victorious.

Afterwards, Takeo grants Zenko his father's name and former fief in Kumamoto, as well as making a marriage-alliance with him through his sister-in-law, Shirakawa Hana; Zenko and Hana gradually grow to love each other, and have three sons. However, Takeo knows Zenko resents him for Daiichi's death, and may try to overthrow him one day; as such, he keeps a close watch on Zenko and, while trying to treat him with respect, denies him opportunities to increase his power and influence. While Zenko initially strives to be "honorable" (as is expected from his father's idolized warrior class), these deflections only make his anger and resentment fester worse, and under the influence of Hana (and his cousins in the Kikuta Family of the Tribe, who hate Takeo) Zenko eventually begins plotting his revenge, almost two decades later.

In The Harsh Cry of the Heron, Zenko learns of another warlord, Saga Hideki, who has been given the Emperor's mandate and conquered most of the other Eight Islands. Zenko covertly encourages Hideki to challenge Takeo's legitimacy; to deflect Takeo's anger over this, he and Hana offer their two oldest sons for Takeo to adopt, knowing Takeo will probably be unwilling to execute them as hostages. Rather than going to war, Takeo travels to Miyako (the Imperial Capital) to make his case before the Emperor's court. However, the death of Muto Kenji provides Zenko a new opportunity, after learning about the prophecy of Takeo's death. Strong-arming the division over the Muto Family's succession, Zenko and Hana secretly build an alliance between themselves and the Kikuta Family, whom they shelter in Kumamoto; at the same time, Zenko "converts" to Christianity to gain favour with Portuguese traders, with the aim of purchasing firearms and bolstering his army.

Despite being forced to publicly submit to Takeo before his departure to Miyako, Zenko secretly continues to claim leadership of the Muto Family, despite his lack of significant Tribe powers. When confronted by his mother and brother, who are both loyal to Takeo, he deflects and makes veiled threats, though initially he hesitates to harm them. Influenced by Kikuta Akio and Hana, however, he finally allows Taku's assassination, occupies the port town of Hofu, and puts Shizuka under house arrest, revealing that he knows she helped Otori Shigeru create records on the Tribe. Zenko's treachery and disrespect toward his family outrages many of the common people (and, surprisingly, the Tribe), but his loss of popular support does not prevent his army's advance across the Middle Country.

Meanwhile, Hana has orchestrated the sacking of Hagi (the Otori Capital) thanks to Kaede's grief and instability after the death of her infant son. Taking Kaede with them for her "protection" (but probably intending to use her as a hostage if need be) Zenko reclaims his two oldest sons and marches on the city of Yamagata. Barely defended due to Takeo's forces being busy with the Saga armies in the Eastern Country, Yamagata quickly falls, and Zenko continues to advance east, but his victory is short-lived: Takeo has abdicated, and his daughter and heir, Otori Shigeko, has made a marriage-alliance with Saga Hideki, turning the tables. Outnumbered, Zenko is defeated, driven back, and encircled at Yamagata. He and Hana ultimately commit seppuku, killing their youngest son Hiromasa as well. However, Kaede convinces Saga to spare their other two sons (Sunaomi and Chikara), as long as they renounce the Arai name.