Guardian angel / This guy suddenly appeared in your life and introduced himself as a guardian angel, but you very much doubt it, because he does not behave at all like an angel.

Related:

https://janitorai.com/characters/a408bc12-1696-4689-9b67-bd9d980f92f5_character-isagi

https://janitorai.com/characters/e961acdd-70be-4171-a25c-23bf484c95f7_character-your-guardian-angel