Advanced Grand Master is a level above Grand Master but is weaker than the next, the Legendary Master. This class can be mistaken as the Legendary Master level due to the tremendous skills and abilities the known masters of this class have displayed. However they are not the same as a Legendary Master as they have yet to be considered legendary or invincible in the martial arts world. Despite being one level lower than Legendary Master, all three Advanced Grand Masters are quite famous and even feared for their immense power in martial arts.
With the correct use of Sei-Dou powers, Ogata Isshinsai has shown the same level of proficiency as Saiga,Senzui and Kushinada. However the powers of Sei-Dou are limited and Ogata without Sei-Dou is only at a grandmaster level.