What is the Supreme Domain?
It's far from any ordinary ability.
In the Demon Slayer World, the Supreme Domain is considered a realm attainable only after one has pushed themselves to their limits and endured pain.
Akaza spent hundreds of years pursuing this domain but failed to reach it until his death.
Not all the nine pillars of the Demon Slayer Corps reached this domain in the final great battle; many had not even touched it.
This ability, even Reiger, was awakened only after undergoing countless hardships while improving the Sun Breathing technique, and Kamado Tanjirou, the original protagonist, didn't even awaken this ability due to Reiger's arrival.
Thus, in the three-piece set of Demon Slayer abilities, the Supreme Domain is the hardest to awaken, the hardest to possess, except for Tsukiguni Yoriichi, who was born with the natural ability to awaken the Supreme Domain. The rest of them went through incredible trials before finally awakening it.
