u/Adventurous-Can3356

i'm searching for a manga I have red around 2018,2019, in french.

the story is set in a school where characters have to survive trials with the power of a kanjis they have chosen. the ambiance is dark and a lot of character dies. the first antognist is another student who can steal body parts of people, and one of the main characters is immortal due to it's kanji. there's also a character called yama. the whole thing is supervised by a mysterious organisation. i think it has a title entirely in japanese