Happy! (ハッピー!?) is a sports manga by Naoki Urasawa about a teenage heroine who embarks on a career as a professional tennis player to repay an enormous debt incurred by her brother to Yakuza loan sharks, with the threat that if she fails, they will force her into a life of prostitution at a soapland.
- Miyuki Umino
- The heroine of the story, Miyuki is a tennis prodigy, capable of beating one of the top tennis players in Japan even while when out of practice. She has a pure heart and is devoted to her family above all else, but her desperation and the schemes of those around her quickly give her a terrible reputation as a "bad girl of tennis".
- Ieyasu Umino
- Miyuki's brother disappears right after the start of the manga but his ill-considered business schemes, are what create the huge debt that Miyuki must pay off. He feels guilty about causing the deaths of their parents and his get-rich-quick schemes are an attempt to make up for the poverty he inflicted on his siblings.
- Junji Sakurada
- The Yakuza debt collector who shadows Miyuki and her career was himself once an aspiring athlete and is alternately threatening, supportive and discouraging. He hopes she can succeed and drags his feet when his superiors pressure him not to give her a chance, but he regularly points out the almost certain futility of what she's doing.
- Kaku Okiku
- A promising young tennis star who is Miyuki's first opponent and becomes a fervent advocate of the prodigy after losing to her. Kaku is a lesbian who is at least somewhat in love with Miyuki and this is used to spread malicious rumours that Miyuki has seduced Kaku.
- Keiichiro Ohtori
- The son of one of the grande dames of Japanese tennis, he went to school with Miyuki and she turns to him for assistance getting her tennis career started. He is thoroughly under the thumb of his tyrannical mother however and this limits the assistance he will give her. He is a good tennis player but his mother decides he lacks the potential to be the best and forbids him to pursue a professional career in tennis.
- Utako Ohtori
- Keiichiro's mother, she was once the champion of Japan. She is rich, vain, callous and vengeful, hating Miyuki for being the daughter of the man she couldn't get. However she agrees to sponsor and train Miyuki in order to use her to embarrass the rival Ryugasaki family. Miyuki's bad reputation starts with Utako's teaching Miyuki a very unsportsmanlike maneuver on the tennis courts and insisting that Miyuki use it to humiliate her opponent.
- Choko Ryugasaki
- The daughter of Hanae Ryugasaki, Utako's rival from Kyoto, Choko is also Miyuki's unscrupulous arch-rival who delights in sabotaging Miyuki with cruel practical jokes and scurrilous rumours. She portrays herself as a cute and innocent victim of Miyuki's wickedness.