Tsukasa Domyoji (道明寺 司,Dōmyōji Tsukasa) was the de facto leader of the F4 and the heir of Domyoji Group. His best friends were Rui Hanazawa, Sojiro Nishikado, and Akira Mimasaka, whom he had known since their childhoods. In high school, Tsukasa met Tsukushi Makino, one of the few people to stand up to him. After several trials and tribulations, they became a couple and were engaged.
Tsukasa was born on January 31 into the Domyoji family as the future heir of the mega conglomerate, Domyoji Group. He was close to his older sister, Tsubaki. She would often physically hurt in order to keep him in line. Nevertheless, Tsukasa missed her when she married and moved to Beverly Hills.
After middle school, Tsukasa went on to Eitoku Senior High with his friends, now called the F4. At some point, they took control over the school and only wore street clothes. They also began handing out red cards, their "declaration of war", to those who defied the F4, including Kimoto. The red card was a signal for the other students to start bullying the individual.
Tsukasa: "You don't mean that! Just who do you think you are, pauper?! I'm name-brand from head to toe! What about you?"
Tsukushi: "I'm no name brand. I'm just me. That's all"
Tsukasa first met Tsukushi Makino, a poor student at Eitoku, after her friend fell down the stairs and landed on him. He refused to forgive her and threatened to give her a red card. Tsukushi defended her and insulted the F4 by saying "you [have] never had to work for anything you [have] got." In response, they gave her a red card the next day. Tsukushi defied them by deciding to fight and declaring her own war on the F4. At first, he allowed the other students to bully her, hoping this would drive her away. Tsukasa quickly became determined to force Tsukushi out of the school. He was also offended when Sojiro and Akira compared her to Tsubaki. His next move was to hire four Eitoku students to assault Tsukushi.
The attempted assault failed as Rui protected Tsukushi. The next day, Tsukasa was kicked by Tsukushi in retaliation. Before passing out, Tsukasa mumbled something about his sister. Tsukushi's popularity among her classmates grew after this incident. Tsukasa was brought out of his state of shock by this revelation. He then decided to have her kidnapped. He brought her to his mansion, where she was given a makeover at his home salon. Tsukasa clumsily offered to allow Tsukushi to hang out with him, though only when no one else was around. She rejected by saying "I [am] not for sale". Despite being spurned, Tsukasa was still attracted to Tsukushi. He soon became convinced that Tsukushi was in love with him, especially she said "I [am] still a virgin." However, her saying this was actually a misunderstanding.
A day or so later, Tsukasa saw Yuriko Asai, Minako Yamano, and Erika Ayuhara bullying Tsukushi. He became angry, yelling "The only one allowed to bully this girl is me!" They quickly ran once he threatened to give them red slips. In a unusually kind manner, Tsukasa said "Don't cry. It's not like you" and offered her his hand. Tsukushi pushed him away instead, telling him that it was his fault she was in that situation. He asked her "what [was] wrong with [him]" for her to treat him this way. Tsukushi then listed everything she hated about him, including his hair, before running off. The following morning, Tsukasa spent five hours straightening his hair. His efforts were rewarded, when Tsukushi said "it suits you". To his frustration, his hair started to curl within seconds.
Tsukasa: "You make me sick you two paupers giggling together! "Someone so good!" Makes me want to puke!"
Tsukushi: "He is good! He's my oasis! The only one who cares how I feel!"
Upon Shizuka's return, the F4 excitedly greeted her. They took her to restaurant that night. Sojiro noticed Rui's sullen mood. Tsukasa commented "He always gets into a bad mood when he [is] happy", which Rui denied. The next day, Tsukasa tried to tease Tsukushi about her braids, but she ignored him. He later saw her talking happily with Kazuya Aoike, which made him jealous. Tsukasa had a red slip placed in Kazuya's locker. When Tsukushi confronted him about it, he yelled "You just don't get it!" The two argued intensely, ending in Tsukasa slapping her after she declared "I like him!", referring to Kazuya. She then punched him, which knocked Tsukasa out. Later, the F4 and Shizuka were having lunch in the university's cafeteria. Tsukushi and Kazuya suddenly busted in, being chased by a group of bullies.
When Rui protected Tsukushi, Tsukasa became angry and questioned his actions. He then said "You don't mean to tell me, you actually like this little pauper", which Rui did not answer. Tsukasa tried to pry Tsukushi out of his arms, turning it into a tug-of-war until they dropped her. He ended the exchange by shouting "we [are] through" at Rui. The next day, Tsukushi was out sick so Tsukasa visited her at her house. Her parents were enamored by his family name and invited him to stay for dinner. Tsukushi was surprised by his nice manners throughout the meal. Her mother forced her to walk Tsukasa to his car. On the way, he asked Tsukushi if she was going on the Hawaii trip and offered to pay for her to go. She refused since she had decided to go to Atami with Kazuya instead. The following morning, Tsukasa announced to Sojiro and Akira that they were going to Atami.
Tsukasa and his friends arrived in Atami on his yacht, surprising Tsukushi and Kazuya, who happened to be at the beach. He pretended that him coming there was a coincidence, stating that Atami was "the place to be". That night, Tsukasa had his hair straightened before the party. Shortly after Tsukushi entered the party, someone turned off the lights. She stumbled in the dark and accidentally kissed Tsukasa.
Tsukasa's most notable trait was his extremely curly hair. His hair could be straightened for brief periods of time, though it would curl again in the blink of an eye. Despite his odd hairstyle, Tsukasa was still considered good-looking by his peers. F4, shortened from Flower 4, was a reference to his and his friends handsome faces.
He is voiced by Takumi Nishio, the first person to portray Tsukasa, in three drama CDs. Yoko Kamio was happy with his performance and felt "he caught that slightly dopey drawl of Tsukasa's". Upon telling Nishio and Takuya Kimura (Rui's part) that they fit the character's images, Kimura jokingly told Nishio that Kamio said he was as stupid as Tsukasa.
Jerry Yan portrays Dao Ming Si, a version of Tsukasa, in Meteor Garden (2001). Si falls in love with Shan Cai (Tsukushi) and pursues a relationship with her, despite many hurdles. Yan's portrayal closely follows the original manga, mirroring Tsukasa's personality and actions.