Wandering Son (Japanese: 放浪息子, Hepburn: Hōrō Musuko) is a Japanese manga series written and illustrated by Takako Shimura. It was originally serialized in Comic Beam from the December 2002 to August 2013 issue, and published in 15 tankōbon volumes by Enterbrain from July 2003 to August 2013. The series is licensed in English by Fantagraphics Books, which released the first volume in North America in July 2011. A 12-episode anime adaptation produced by AIC Classic and directed by Ei Aoki aired in Japan between January and March 2011. Eleven episodes aired on television, with episodes 10 and 11 edited into a single episode, and were released individually on their respective BD/DVD volumes.

The story depicts a young trans girl named Shuichi Nitori, a student who develops a close relationship with another transgender classmate, a young boy named Yoshino Takatsuki. The series deals with issues such as coming to terms with being transgender, finding one's gender identity, the onset of puberty and gender dysphoria, and the social pressures associated with being transgender. Shimura was originally going to write the story about a girl in high school who wants to be a boy, but she realized that a boy who wants to be a girl before entering into puberty would have many worries related to growing up, and changed the story to fit this model. Wandering Son was selected as a recommended work by the awards jury of the tenth Japan Media Arts Festival in 2006. The series has been lauded for its exploration of gender identity and its depiction of transgender characters at the core of the story, though the emotional realism of the young characters has been called into question.

At the start of Wandering Son, Shuichi Nitori is a student in the fifth grade who transfers into a new school. He quickly becomes friends with another student: the tall, boyish Yoshino Takatsuki. Yoshino soon learns of Shuichi's desire to be a girl. In a show of friendship, she confesses a similar desire to be a boy. Shuichi also becomes friends with Saori Chiba and Kanako Sasa, two other girls in the class. Saori instantly takes a liking to Shuichi and continuously encourages her to wear feminine clothes.

After Shuichi, Yoshino, and their friends enter sixth grade, Shuichi meets Makoto Ariga, another student their age from another class who also wants to be a girl. Shuichi and Yoshino become friends with an adult named Yuki, who is a trans woman living with a man named Shiina. Shuichi's older sister Maho becomes a model and eventually becomes friends with Maiko, a teen model whom she idolizes, and two other teen models: Tamaki Satō and Anna Suehiro. Maho gets a boyfriend, Riku Seya, and Shuichi confesses a crush on Yoshino, but Yoshino cannot reciprocate Shuichi's feelings. After Saori learns of this, she confesses she likes Shuichi, but Shuichi too cannot return her feelings. This results in a falling-out between Shuichi's friends as they prepare to enter junior high school.

In junior high school, they meet a tall, eccentric girl who befriends everyone, Chizuru Sarashina, and her prickly friend Momoko Shirai, who does not get along well with the others—especially Saori. Eventually, Saori and Yoshino rejoin Shuichi's group of friends, though Saori says she still hates Yoshino and Momoko. Shuichi and Anna start dating, much to the surprise of their friends and Shuichi's sister. Yoshino and Saori manage to halfway repair their friendship, though Saori is still standoffish to others. Shuichi's friends are split up into several classes upon entering their second year in junior high school. Shuichi becomes friends with Shinpei Doi, who previously teased her about wanting to be a girl. Yoshino attends school in a boy's uniform for a short time, and Shuichi tries to go to school dressed as a girl one day, but is laughed at, and they both become discouraged. Shuichi's friends worry as she begins skipping school. Although Shuichi eventually starts attending school regularly again, Anna breaks off their relationship. By the time Shuichi, Yoshino, and their friends enter their third year in junior high school, Shuichi's voice is changing which causes her dysphoria to worsen. The group of friends start thinking about their future high school plans, and Shuichi and Anna start dating again.

Shuichi begins attending the same all-boy high school as Makoto and Doi, while Yoshino and Saori begin attending a high school where uniforms are not required. Saori starts dating Fumiya Ninomiya. Yoshino starts working at Anna's modeling agency and Shuichi begins working at a cafe, but later quits. Shuichi starts writing a semi-autobiographical novel. Yoshino later tells Shuichi that they no longer wish to be seen as male and have decided to continue living as a girl. They also confess a romantic attraction to Shuichi and the pair briefly hold hands before saying goodbye. Shuichi informs Anna of her true gender identity, and much to her surprise Anna decides to stay in a relationship with her. After graduating from high school, Shuichi moves out and goes to the same college as Doi. Shuichi continues to write the novel, which is given the title The Boy Who's a Girl (ぼくは、おんなのこ, Boku wa, Onna no Ko).

In an interview in August 2003, Takako Shimura stated that the theme of Wandering Son is similar to the second half of her previous manga series Shikii no Jūnin. Shimura took the junior high school teacher Kentarō Kaneda from Shikii no Jūnin and inserted him into Wandering Son, where he teaches at Shuichi's junior high school, because she really liked his character. Shimura originally planned to use a female high school student who wants to become a boy as the main character. However, she realized that a boy who wants to become a girl before entering into puberty would have many worries related to growing up, and changed the story accordingly. Shimura used her realization that the boy would go through significant changes as he grew up to deepen the development of the story and characters. The Japanese title, Hōrō Musuko, is a pun on hōtō musuko (放蕩息子), meaning "prodigal son".

Shimura mainly found her characters' names by looking through name dictionaries, although she also took the names of acquaintances and slightly changed them, and even used train station names for side characters appearing only once. Out of all the characters, Shimura is most pleased with Kanako Sasa. For the designs of clothes for the female characters, Shimura consulted various fashion magazines for girls in their early teens, especially Nicola. Shimura commented self-deprecatingly in the afterword of volume one that, like her other series, her characters do not look very different from each other, her panels are too white, and there is much pathos.