The new manga spin-off My Hero Academia: Team Up Mission is coming this month, according to Weekly Shonen Jump magazine, issue 33 of this year, published yesterday.
As seen on Anime News Network, the manga will start with a prologue chapter to be published first on July 25 in Shueisha’s Jump Giga magazine, Summer Volume issue 2. This release will coincide with the fifth anniversary of the franchise.
Then, Team Up Mission will start publication in Shueisha’s Saikyō Jump magazine on August 2.
Later this year, the fourth season of the anime starts on October 12, to be followed by a film on December 20.
[Source]: Anime News Network: My Hero Academia Gets New Spinoff Manga This Month.