The 12th issue of Shueisha’s Weekly Shonen Jump magazine revealing on Monday Yusei Matsui's Assassination Classroom manga will end in five more chapters. Specifically, it will end at the 16th issue of the magazine, which will be released next March. Moreover, manga’s end coincides with the end of the academic year in Japan and graduation season. Weekly Shonen Jump is also starting a "graduation countdown" for the manga in the 12th issue and the 16th issue will include a comment and an illustration by Matsui regarding the manga's ending.

The manga debuted in July 2012 and so far, it has sold over 20 million copies in print. The first anime series was released on January 2014, while the second premiered last January. There was also a release of live-action adaption last March and a second will open in Japan on March 25. 

Source: animenewsnetwork.com