Nagisa and Karma travel to the International Space Station in hopes of learning the secret to saving Koro Sensei's life. Meanwhile, Yanagisawa and the upstart Grim Reaper II train ever harder to assassinate him. Then, when academic setbacks lower the spirits of his students, Koro Sensei comes up with an ingenious—or perhaps idiotic—way to cheer them up. Next, Valentine's Day arrives! Will any of the 3-E students or teachers find true love? And will the meddling and teasing of the others help or hinder Cupid's arrow in finding its target…?

Volume 18 of the Assassination Classroom manga series by Yusei Matsui.