The Offer of a Lifetime

Nagisa Shiota has felt out of place in the Assassination Classroom for quite some time and felt he was getting in the way.
When an offer to go abroad is given to him, Nagisa accepts and decides to leave his life behind to start one of an assassin.
His classmates find out and it's up to them to stop him before it's too late.
Will they complete their new mission or will they say goodbye to Nagisa forever?
Karmagisa shipping.
(cover and characters aren't mine)