Shimotsuki Yasuie, also known as "Yasu the Hedgehog", Tonoyasu, or just Yasu, was a member of the Shimotsuki Family, and a taikomochi who lived in Ebisu Town near the capital of Wano Country. He was the father of Toko. Back when the Kozuki Family ruled over Wano Country, Yasuie served as the daimyo of Hakumai. Twenty years after Kurozumi Orochi's takeover of Wano, Yasuie sacrificed himself in an effort to mislead the shogun's forces and enable Kozuki Momonosuke's revolution to continue. Yasuie was a thin short man with a thick spherical head. He had tiny blush marks on his cheeks, stubble around his mouth, and a thin mustache on his upper lip. Like the other residents of Ebisu Town, he was always smiling due to having consumed a faulty SMILE Devil Fruit. His epithet came from how his thick blue afro spiked out like hedgehog spines. Kanjuro and Shinobu did not recognize him until they saw it. As Tonoyasu, his hair was covered by a bandana with purple polka-dots and tied in a top knot. He wore an orange kimono with stitched patches and waraji sandals. Over 25 years ago, Yasu's face was much cleaner and less spherical; he wore a dotted kimono with a dark robe over it. He also appeared to be much taller than he was in the current storyline. Due to eating a failed SMILE, Yasuie was always shown smiling. He was very easily excited, as he gushed over Zoro's accomplishments and showered the swordsman with compliments. He could also be self-deprecating, as he did not object when Zoro accidentally referred to him as "Kasu" (trash) instead of "Yasu".
Though eccentric, carefree, and fun loving, Yasuie was extremely kind and compassionate, using the money his daughter earned to support the citizens of Ebisu Town, providing provisions to those who are too sick and injured even if it means starving himself. He enjoyed helping people, even those as amoral as Bingo, Bongo, and Bungo. His friendly and compassionate personality gave him a strong charisma, as when he joined the conversation with Kanjuro and Shinobu about the rebellion, neither of them brought up the fact that they did not know who he was. According to Shinobu, he was a strict man in the past, but lost much of that attitude over the last 20 years. He took his position as daimyo extremely seriously, especially when it came to protecting the Habu Port. In much of the same way, he expected Kozuki Oden to devote his time proving himself as Sukiyaki's heir. He was also extremely generous as not only did he gave away all the money to most of the future Nine Red Scabbards tried to steal, he also gave them extra money to them and encouraged them to buy books to educate themselves for the sake of supporting Oden. He was also perceptive as he did not quickly believe Orochi's claim that Oden stole money from him, knowing that Oden was not the kind of person who would hide his misdeeds. Yasuie was proud of his deeds as Tonoyasu. With his last breath, he declared to die not as a daimyo of the Kozuki Family but as a fun-loving jester of Ebisu Town. Toko is Yasuie's daughter. Although the two were separated after Toko was sold off to work in the Flower Capital, they maintained a close bond, with Toko giving Yasuie her earnings from her work. When news about his capture and planned execution reached her, she ran to the Flower Capital, despite being targeted by the shogun. Right before his execution, one of his last thoughts was an apology to Toko for leaving her behind. Yasuie was a strong supporter of the Kozuki Family, so much so, that he was even willing to lay down his life just to be of help to them. Even when the title of shogun was rumored to be going to him by the time of Sukiyaki's death, he acted against it because he firmly believed that only the Kozuki Family should be the ones to have such power. He held very high expectations for Oden because of this and would discipline while he was under his care, to make the late daimyo take his responsibility of becoming the next shogun seriously. As a result, he also believed that Oden's son, Momonosuke, would be the future shogun after Oden. He also stood along the other four daimyos in standing up against Orochi to show their disgust against the shogun’s cowardly ways of claiming his title. After witnessing his demise, Oden's daughter Hiyori broke down in tears. While Yasuie was not against Oden's desire to set sail and traveling overseas, he believed Oden could only do so after he proved himself a great samurai. Even though most of Wano lost respect for Oden during the five years after his return, Yasuie remained on good terms with him. In fact, Oden trusted Yasuie to protect his family when he decided to fight Kaido.
Yasuie is a loyal supporter of the Kozuki Family, and stood by Oden during the Beasts Pirates' takeover of Wano Country 20 years ago. When he came across the secret message Kin'emon sent, he showed his willingness to join the fight to Kanjuro's group immediately. At the time neither Shinobu nor Kanjuro could recognize him and felt awkward to mention that, but when his hair was exposed at his execution site, they realized who he was. Kanjuro also regretted not realizing his identity sooner when he was executed and called his death a grave mistake. Despite not knowing their connection to the Kozuki Family, he provided shelter to Law and the Straw Hat Pirates in his home in Ebisu Town. When the masses started laughing and crying at Yasuie's death, Zoro was furious and tried to stop them, believing it was an insult. After Zoro and Sanji started a commotion, the Straw Hats present at Rasetsu Town retrieved Yasuie's body so he would not be left on display. As the daimyo of Hakumai, he had control over the region and its inhabitants until he lost the position. In the present day, he showed himself to be very conniving and well-spoken, tricking authorities into believing he was Ushimitsu Kozo in order to give himself a platform to trick Orochi and forces. After eating a failed SMILE, Yasuie lost his ability to swim. Yasuie saw the swordsman Roronoa Zoro and decided to follow him, having a good feeling about him and paying for some sushi for him to eat. He believed his decision vindicated when Zoro earned a lot of money gambling and took out some members of the Kyoshiro Family when they decided to stop him. Yasuie gushed over Zoro's accomplishments as they walked toward Ebisu Town. After arriving at the town, Yasuie introduced Zoro to the people living there. He later met Trafalgar Law, Usopp, and Franky after Zoro left to recover the stolen Shusui. After hearing that they were friends of Zoro, Yasuie invited them to his house and informed them that they just missed Zoro. As Shinobu, Law, and Kanjuro argued over what to do about the captured Heart Pirates, Yasuie entered and showed them a copy of Kin'emon's secret message and talked about the rumors swirling around the Flower Capital, wondering if the final battle was at hand. After telling Kanjuro and Shinobu that he wished to join them, he went around Ebisu Town, helping those in need. Before midnight that night, Yasuie went into the Flower Capital to commit robberies in order to pose as Ushimitsu Kozo. He was caught by Orochi's forces, who believed his confession that he was Ushimitsu Kozo. He was taken to the Rasetsu Town prison in the Flower Capital the next morning to be crucified, and he was happy to see that the crowds gathered around him knew who he was. He spoke to Orochi, saying that the Kozuki Family built everything good in Wano and that the current shogun had only ruined it. He then lied that he created the Kozuki Family's secret message as a childish prank, and that the crescent moon symbol that resulted in Orochi making dozens of arrests was a common, unrelated design. As Orochi approached the execution platform, Yasuie cursed him and eagerly anticipated the return of the Kozuki Family. He was then shot multiple times and killed by Orochi and his forces.
