20 years later, Ken and Titania's son Moriko had grown up and Ken had taught him the magic techniques he used himself. Moriko managed to create the space-cutting sword technique with the techniques taught by her father, and her powers gradually increased.
A few days later, the City of Peace was attacked by Demons. This attack heralded the return of the Demon Lord, whom we thought the Demons had defeated years ago.
The Demon Lord was thought to be dead years ago, but in fact he had only faked his death and tried to gather his powers.
Moriko decides to fight the Demons, and her father Ken joins the fight with her to find out if he has taught her well.
When they arrived at the battlefield, the Demon Lord and his soldiers greeted them. Moriko attempts to use her space-cutting sword in her battle with the Demon Lord, but the Demon Lord surpasses her powers and brings her to the point of defeat.
Meanwhile, Ken rushes to the battlefield and summons her to jump just as the Demon Lord directs his attack at Moriko. Moriko wakes up to Ken's voice and jumps, thus avoiding the Demon Lord's attack.
Although Moriko tried to fight the Demon Lord, his powers were too much and Moriko was defeated.
Ken rushed to save his son and began fighting the Demon Lord. They were both very powerful wizards and the war lasted a long time.
In the end, Ken managed to defeat the Demon Lord and save Moriko. The people also celebrated with joy. However, there was something they didn't know.
The Demon Lord brought the virus with him when he came. This virus turned the infected person into a demon. The virus had infected everyone, and something unavoidable had happened. The virus had infected everyone except Ken.
The name of the virus was "Black Death". This virus was taking over people's bodies and turning them into demons. Therefore, Ken was back in the past to destroy the virus. He prevented the transmission of the virus by killing the Demon Lord again, this time he burned his corpse to prevent it from being transmitted.
In the end, Ken and the others had destroyed the Black Death virus, eliminating the future threat. However, this was not the end of the war. The demons were still there and might attack again one day.
Therefore, Ken and the others were ready to fight against demons and always tried to improve their powers. The battle to keep the City of Peace safe would continue.