The beings in this world are classified into the following ranks from low to high according to the threat they pose:
1. F Rank
2. E Rank
3. D Rank
4. C Rank
5. B Rank
6. A Rank
7. S Rank
8. SS Rank
9. SSS Rank
10. EX Rank
11. Transcendent Rank
12. Divine Rank
13. Cosmic Rank
14. Beyond Cosmic Rank
15. Concept Rank
These ranks will also have + or - added before them depending on whether they are stronger or weaker than their supposed rank but is too weak to be ranked in the higher rank or too strong to be ranked in the lower rank.