Slam Dunk: Sakuragi learned from Kawamura Eiki's experience

Sakuragi Hanamichi, a junior high school student, keeps having a strange dream. In his dream, he's playing basketball in an arena called the NBA, but he's always on the bench. He also dreams of himself as Kawamura Eiki, a short guy. Then, Sakuragi embarks on his basketball journey a year early. (No time travel, no system; just the story of junior high school Sakuragi gaining basketball experience from the future Kawamura Eiki.)