A school-life manga where everyone is given a word, which becomes their power to survive against monsters

Question

I'm looking for a manga I read about 4-5 months ago. I can't remember the names of the characters. These are what I can remember:

• It is about a school which only accepts students who can see an island in the sky.
• On the first day, everyone was given a word which turned out to be some kind of power. The main character got the word which allowed him to change his appearance to that of other people.
• Most of the student were killed in the first day by some kind of monster, and there were monsters appearing everyday (except for rainy days).
• There was one student who got the word which made him immortal. Another one got the word which gave him the ability to steal anything (heart, brain, etc.)

Answer 1

Sounds like you're looking for Aphorism

• It is about a school which only accepts students who can see an island in the sky:

  Welcome to Naraka High School, where every graduate is guaranteed a bright future. Seriously. Just by graduating, your status will be greatly raised, and can even become a bureaucrat without ever needing to go to college. Entry requirements? If you can see the floating island, you’re accepted.

• On the first day, everyone was given a word which turned out to be some kind of power. The main character got the word which allowed him to change his appearance to that of other people.

  Rokudou Momiji is a kid who does not matter, an absolute nobody. He has never been smart enough, or fast enough, or even tall enough, and he wants to change that, since he’s going to high school, and especially since he’s met a girl he wants to impress. So on the first day of high school, when the students are tasked with writing down “a character (kanji) that they will need for the future”, he writes down the kanji for “change”.

• Most of the student were killed in the first day by some kind of monster, and there were monsters appearing everyday (except for rainy days).

  Monsters start oozing out from the ground, and all the students are forced to start fighting for their lives. ... When it’s over, more than half of the student population has been killed, and there's more: every time the floating island aligns with the sun, something like this will happen, and every time it happens, students will be expected to fight for their survival.