This is no hoax, the author of the series himself was the first to announce the project.
Fans of the classic basketball manga and anime Slam Dunk is finally getting an anime movie. Series creator Inoue Takehiko tweeted the announcement with an animated image scribbling the Slam Dunk title along with the message “It will be a movie!” and the hashtag #SlamDunkMovie. Soon after the official website for the movie went online adding more legitimacy to the announcement.
— 井上雄彦 Inoue Takehiko (@inouetake) January 7, 2021
Based on the initial details, the movie will still be an anime and will be produced by Toei Animation, the same team that handles the anime series in the ’90s. Inoue previously released. No info was revealed on who will be the director, story plot and the official movie title as of this moment.
Slam Dunk is about a delinquent student named Hanamichi Sakuragi who joined Shohoku high school basketball team after being convinced by his crush and his journey to becoming the best rebound player start. The manga has released 31 volumes and sold over 121 million copies worldwide, it spawned an anime adaptation lasting for 101 episodes along with 4 short films. The series became a phenomenal hit in Japan and other countries such as the Philippines, Taiwan that made basketball a popular trend at the same period when Michael Jordan and the Chicago Bulls were the hottest team.