Review Detail of Imperial_Crest in Magic Era: My Cells Can Evolve

First Author said there were no 6-Tier magicians and that they were the very top of the humanity. Humanity had no one stronger than 6-Tier magicians. But then 10 chapters later, we were told there are 7-, and 8-Tier magicians as well but no 9-Tiers. In the same sentence, we were told that there are no God-Tier magicians. "Therefore, there was a saying that it was called City Protector Tier-Six Magister, Border Protector Tier-Seven Magister, Kingdom Protector Eight Magister!!"