Haruko Akagi (赤木 晴子, Akagi Haruko?) is Takenori's younger sister and Sakuragi's love interest.
Sweet and with a captivating personality, she is always around to cheer on the players, especially her brother Takenori, who is extremely protective of her and taught her the basics of basketball, and Sakuragi, whom she considers her best friend. Haruko often appears at matches together with Sakuragi's cohorts and her two best friends, Fujii and Matsui. She, like most girls in Shohoku, only has eyes for Rukawa, although he never reciprocates her feelings and, later in the anime, she acknowledges that he will not love her the way she wants him to and tries to let go of her crush, however unsuccessfully.
Haruko was responsible for uncovering Sakuragi's athletic talent after seeing him try to dunk a ball at her request - she was impressed by the height of his jump and considered him good enough to join the team. Sakuragi always listens to her due to his deep affection for her. They have gone on some (what Sakuragi considers) non-official dates and have occasionally trained together.
Despite her emotional denseness and sweetness, Haruko is a pretty good student, helping Akagi tutor Sakuragi and the other three starters when they had to retake some tests they had failed or be disqualified from the National Tournament, and is not afraid to stand up for others when needed. She confronted Sakuragi when she mistakenly thought that he had attacked Rukawa, and she also defended him many times from his most rabid fangirls (one of them even knocked her to the ground in the anime series).
At the end of the manga series, Haruko becomes the second manager of basketball team. She is voiced by Akiko Hiramatsu.
- She likes Rukawa because of his look and genius in basketball
- She was the first person to believe that Sakuragi has a potential on playing basketball
- She stated that she hated the girls that always cheer on Rukawa
- She always squeels or gets heart strucked when Rukawa gets points
- She is always worried about Sakuragi