i think it's going to be about like. the meaning of life/being alive if that makes sense. at the start of the story the protagonist is suicidal until she's thrown into a situation as miserable as the ceremony and she slowly gains the will to live (according to the interview)

also we have a character like maria who believes death is salvation + shii who is obsessed with success and failure and probably can only find worth in her life if she's successful (+ her flower literally means rage in hanakotoba so it probably really affects her)