Hanabi's childhood friend was short-tempered and pushy, yet sweet. They had been friends since birth and were next-door neighbors. He claimed he practically raised Hanabi. He trained her to be strong, shaping who she is today. When Hanabi started elementary school, he moved to Denmark due to his father's work but promised to return when she became truly strong. Ten years later, he returned to Japan to keep his promise. He visited briefly to look for houses in the area and told Hanabi to break up with her boyfriend to be with him. He took her to a love hotel to 'make her a woman,' but they didn't go inside. However, they were seen by Hanabi's schoolmates, who misunderstood and spread rumors around school. Yasuaki quickly squashed the rumor by saying Hanabi was just showing an old friend around town.
Despite this, Yasuaki was still jealous and spoke harshly to Hanabi, assuming she and Takeru were together. She got upset and declared that she chose Takeru, unwilling to hear more of Yasuaki's mean words. When Hanabi went to tell Takeru her decision, she found out that Takeru and Yasuaki had gotten into a fight. She immediately ran to Yasuaki, realizing who she truly wanted. Yasuaki admitted to being jealous of Takeru, mentioning that they acted and talked similarly. Takeru asked Hanabi to meet him at the airport to answer his confession, but she called him instead and told him she chose Yasuaki. He advised her that trying something new might actually be fun. Later, Takeru returned, showing no signs of backing down. He took Yasuaki and Hanabi to pick up Hanabi's father from the airport.
Hanabi's father initially had bad impressions of Yasuaki and said he preferred Takeru, even calling them 'Takebi.' It turned out he was only testing Yasuaki, who passed his test, earning his approval for their relationship. Finally, Hanabi stood up to Takeru when he offered to pick her up and take her home, but she declined, choosing to spend the night with Yasuaki instead.
