Assassination Classroom volume 9 features story and art by Yusei Matsui.

Nagisa risks life and limb in an attempt to take down the mastermind behind a biological attack. After the dust settles, Koro Sensei tries to ignite some summer romances between the students of 3-E. Their teacher Irina Jelavitch, at least, has her sights on someone... and everyone happily conspires to bring them together! Back at school, one of the 3-E students defects from the ranks for all the wrong reasons. How will they bring him back before he inflicts irrevocable damage on them all...?