The Twin Gods, Seiren's sacred guardians Katsu and Shi, maintained the balance between life and death together. While Katsu breathed life into surroundings, Shi eradicated the darkness that should not exist in the lands. The gods continued their duties throughout the ages, but they too had an end: they were aging.

The twins, witnessing humanity's millennia-long evolution, were ready to bid farewell to this world. Katsu devised a plan for the continuity of the balance of life and death; he wanted to seal their powers into two swords with his brother and pass on this responsibility to humans. Despite Shi's reluctance, he knew there was no other solution.

They appeared before humans with a significant announcement: 'O people, I am Katsu, the steward of life. This is my brother Shi, the steward of death.

We've upheld the balance of these two concepts for ages for your lives, but now our duty comes to an end.'

The people were astonished. Would there be balance without the gods? Would their peaceful lives come to an end? Unable to fathom a life without balance, they conversed among themselves. Whispers filled the air.

A man with a dirty beard stepped forward and addressed the twins, 'O mighty twins, without you, what will become of us? We express our eternal gratitude for your service... I do not mean to overstep, but aren't you gods, and isn't your duty to ensure our peace?'

A silence fell over the crowd. Everyone awaited the forthcoming response. 'I am Shi, the envoy of death, indeed, we are the guardians of balance and here for your peace. However, as Katsu mentioned, we have reached the end of our duty. The purpose of this address is to inform you of that and to let you know that we bequeath this duty to you,' Shi replied.

Again, whispers spread. From among the crowd, a bespectacled, tall, white-bearded man stepped forward. 'Mighty twins, no amount of gratitude suffices for the years you've dedicated to us, and I'm sure you know this better than us. Yet, I still ask: How can we fulfill this duty? We are ordinary folk; all we can do is till the soil. How can we maintain balance... please, have understanding-' 

"Fret not, human. As you live, you will see your potential and what more you can achieve," said Shi. Then Katsu intervened, "Before we pass on our duty to you, let me explain the preparations for the new order: We shall become the swords of life and death. Those deserving among you will inherit our power and maintain the balance. And thus, it shall continue.'

'But mighty twins, how will we know if we deserve this duty or not? O-or how will individuals become deserving?' The elderly man was in a panicked state.

'Look, we will train you, and one among you will wield the sword of life, and the other the sword of death. They will uphold the balance; after them, new sword-bearers will emerge from the next generation, be trained, and take on the duties.'

"That's enough, human. I don't think you need any more questions," said Shi, and the elderly couldn't utter another word.

"Now, welcome to the beginning of the new order, people." Despite the tension among the people, celebratory cheers erupted around them. And so, the sacred order began. The twins taught the people of the existence of the soul and trained them accordingly. It was time; the twins sealed themselves into swords, leaving their legacy to humans. The chosen ones were trained at the Seitoshi temple, inheriting the legacy. Ages passed this way; the chosen ones were trained, fulfilled their duties, and passed their positions onto new generations. Thus, Seitoshi ushered in a new era, reaching until today.