Sojiro and his friends became known as the F4 by the time they enrolled at Eitoku's high school. They practically controlled the school, and were feared by the students and staff. Partly to amuse themselves, they began giving out red cards, their "declaration of war", to those who stood up to them or otherwise annoyed them, including Kimoto.
Sojiro: "She kinda reminds me of Tsukasa's big sister, before she got married."
Tsukasa: "What are you talking about?! As if my sister could ever look like her!"
The F4 first met Tsukushi Makino, when her friend landed on Tsukasa after falling down the stairs. Tsukushi defended the girl, and accidentally insulted the F4. She was promptly given a red card the next day. She withstood the bullying and challenged the clique by giving them her own "declaration of war." Sojiro and Akira were impressed by her actions, which they found "spunky". They still mused that she would not last long. Later, Sojiro irritated Tsukasa about comparing Tsukushi to his sister Tsubaki. Some days later, he heard about Tsukasa ordering some guys to attack Tsukushi. Therefore, he was not surprised when Tsukushi kicked him in front of the entire school.
Sojiro and Akira later decided to stop bullying Tsukushi, believing it to be Tsukasa's vendetta. This irritated Tsukasa as he could only express his crush on Tsukushi through bullying. The same day, Sojiro and Rui saw Tsukushi at her job. Sojiro teased her a bit then left with Rui to go to a party. A day later, Sojiro was eating lunch with Akira, when Tsukushi walked by. He invited her to join them. Sojiro and Akira then began discussing Shizuka's impending return. Tsukushi asked about Shizuka's and Rui's relationship. They revealed that she was Rui's first love and that she was the one who drew him out of his shell.
The next day, Shizuka came to Eitoku shortly after returning from France. She greeted Sojiro and his friends happily. They later took her to eat and dance at a club. After Tsukushi's friend Kazuya Aoike transferred to Eitoku, Tsukasa gave him a red card without consulting the others. The F4 was eating lunch with Shizuka at the university, when Tsukushi and Kazuya charged in chased by their classmates. When Rui protected Tsukushi from the bullies, Tsukasa became angry at him and declared "we [are] through." He then stopped out and yelled for Sojiro and Akira to follow him. A couple of days later, Tsukasa told Sojiro and Akira that they were going to Atami instead of Hawaii for the summer.
They traveled to Atami on Tsukasa's yacht. Upon arrival, Sojiro was surprised to see Tsukushi there. Shizuka gave Tsukushi a makeover for their party that night. Sojiro was impressed, saying "I knew she [would] shine with a little polish."
After graduating high school, Sojiro began to attend Eitoku University with Akira and Rui. During his second year, he attended Shizuka's wedding in France. While continuing his education, Sojiro became the Grand Master of his family's tea school.
Haruto: "To be honest, there's a girl I like. I don't want to lose for her sake."
Sojiro: "That's more like it. If it were just for Eitoku, I was about to tell you to give up and run away. But if that's the case, that changes things. I'm not against it, if it's for a girl."
Sojiro was asked to participate in an annual horseback archery competition held in Kyoto. He had competed in the contest before. While practicing with an instructor, Sojiro met Haruto Kaguragi, a student at Eitoku. Haruto told Sojiro that he was entering the infamous "Manly Man Festival" against Tenma Hase. He also confessed that he wanted to win because of his crush on a girl. After hearing this, Sojiro offered to help him practice archery. His instruction improved Haruto's skill considerably. Later, Haruto told him that Tsukasa had "entrusted the care of Eitoku" to him. Sojiro laughed and said that Tsukasa would never say anything like that. Haruto later informed him that he won the festival by default, which he was a little depressed about. Sojiro, however, told him "a win [is] a win". He then advised him to go meet the girl he liked.
Sojiro was considered handsome, much like his friends as they were all called F4 (Flower Four). He had short, brown hair that was parted in the middle. His eyes were a similar shade of brown.
Personality and traits
Being characterized as a "playboy", Sojiro was particularly fond of women and parties.
Sojiro is played by Shota Matsuda in Hana Yori Dango (2005), Hana Yori Dango Returns (2007), and Hana Yori Dango Final (2008). Matsuda's portrayal closely follows the manga, mirroring much of Sojiro's personality. In Returns, Sojiro takes over the leadership of the F4 in Tsukasa's absence. His relationship with Sara is also explored in Returns, though it is somewhat altered. By the end of Final, he has become the head of his father's tea school and an author.