Making his first appearance in Chapter 49 of the manga (Volume 9), Manabe initially comes across as a rather lazy but outgoing and joyful young man, a trait that has remained consistent. As the Vice President of Kaibara High School's student council, Kakeru proudly serves as the "second-in-command of the School's Defense Force." He is passionate about his role, often likening it to a Super Sentai job, with him claiming to be "Black" (like the black Goranger) while Yuki is "Red" (the leader). Manabe shares striking similarities with Ayame Souma, Yuki's older brother, whom he hugged upon meeting, declaring no one else could be the Defense Force's commander. Yuki also notes that Manabe, like Kyou, excels at making friends.
Despite his outwardly cheerful demeanor, Manabe occasionally struggles with self-esteem issues and can become serious when necessary. He is fascinated by the Sohma family's beauty, frequently asking various Sohma members for their secret to handsomeness.
Manabe is also the half-brother of Machi Kuragi, the quiet and thoughtful treasurer. He is protective of her, often seen ordering her around out of love rather than sibling superiority. They share the same father but have different mothers. According to Kakeru, he is the illegitimate son, and because he was older and the only son, there was a heated dispute between their mothers over inheritance. Machi's mother pushed her to be perfect, hoping she would become the family's heir. However, after Machi's younger brother was born, she was sidelined. This led Kakeru to feel responsible for taking care of Machi, believing she had been treated unfairly. At one point, Kakeru told Yuki that he realized how pointless the inheritance dispute was and refused to participate, shouting, "I'm not gonna play your stupid game anymore!" This made his mother realize he was right, and he felt "officially free," though he noted that Machi might not have gained her freedom yet.
Although Machi and her mother still need to resolve their issues, Kakeru and his mother get along well, though they regularly argue loudly about trivial matters, causing complaints from their landlord. His mother seems to have moved past caring about the inheritance.
Due to his vice presidential status, Manabe is closely associated with Yuki Souma, the student council president. Despite their obvious differences and occasional personality clashes, they have developed a strong bond. In later parts of the manga, they are seen smiling together more often, rather than just Manabe teasing Yuki or falling asleep while Yuki speaks.
