Yoshino, the other protagonist, is tall and masculine, and at the beginning of Hourou Musuko is a fifth grader in Shuuichi's class. Otherwise known as Takatsuki-kun by his classmates, he is a transgender boy and usually refrains from dressing in traditionally feminine clothes such as skirts or dresses, in spite of his mother's insistence on buying him such clothes. Shortly after meeting and becoming friends with Shuuichi, Yoshino cuts his hair to a very short, boyish style, giving him the appearance of a boy his age, especially when he dresses in a male school uniform. Like Shuuichi, Yoshino becomes increasingly concerned and resentful about his changing body due to puberty such as when he begins menstruating or when his breasts begin to grow. He even goes so far as to buy a garment to flatten his chest so that he does not have to wear a bra.

While Yoshino would like to dress and act like a boy all the time, he usually abstains from doing anything overt which would draw attention to himself such as going to school in a male uniform once he begins junior high. However, he does on occasion dress in a male school uniform and go to neighboring cities presenting as male, and during one such time enjoys the fact that he is hit on by an older woman. Yoshino wants to look "cool" if he can, wearing clothes which make him look less like a girl. When teased by others, Yoshino is prone to getting emotional, and is also known to get violent on occasion. Yoshino takes up an interest in basketball after entering junior high school, and joins the female basketball team with Chizuru Sarashina. In junior high, Yoshino grows his hair out after a comment by Saori, but later cuts it back again to a short, boyish style. His family consists of his father, mother, older brother, and older sister.