It's a manga I read a long time ago, I don't remember the name or author.

It's a special school, the teacher asks the students to write on a piece of paper the answer to the question "What would you think will help you to survive" or something like this.

The main character (boy) writes 'sword', something happens and the boy can summon a sword to fight.

Whatever was write in the paper became a kind of 'power' to fight against some creatures (I don't remember).

Thank you.

Perhaps Aphorism?

Oh, yes! It is!

lol I thought the boy has the sword, but he chooses 'change'.

Thank you very much!