One day, an earthquake struck, followed by a tsunami.

The students managed to escape, but Mr. Abe was left behind.

Realizing he wouldn't make it, Mr. Abe sent this message to another teacher.

"Please show this to the students. If you are reading this, I am likely no longer in this world. If I'm actually alive, this is going to be so embarrassing, haha. But I'm probably gone. Thank you for everything. Now, I'll give you your final homework assignment...! First, don't forget about me! Second, work hard once you graduate! Third, have a dream! Fourth, stay together forever! Fifth, live your lives to the fullest. That is all. The answer sheet is your future lives. The due date is when your time on earth is done. You will be the ones to grade it yourselves. When you become adults, when you get married, when you have children... I'll become a butterfly or something and come visit you. See you later, okay? From Mr. Abe"