[Cover art made by me!] 3 years after "The End". The Masquerade of Sickness, also known as The Bevissthet Plaque was started by an overpopulated area of pufferfish.
Fishers there would catch the fish and when they did, the pufferfish would release TTX or Tetrodotoxin in a way to warn the other fish.
This happened so many times that the remnants of the poison remained in the air, and spread all throughout Norway, then every other country. Since no gas masks or plague doctor masks were available, Tord, the army leader and world conqueror (also known as the Red Leader), came up with an idea to use full face masquerade masks. The mask's nose and mouth would have small air purifiers, just like a gas mask.
And the eye holes would be covered with a material that blocked anything from getting into the mask. That way, they wouldn't have to worry about TTX infection in the eyes.
These masks were available world wide .. well, I say that. Their supply of masks to England was cut off.
Lost. Forever. There wasn't another supply boat they could send. So in a last attempt to keep everyone safe, they took in as many people as they could. Including the leader's old friends; Matt, Edd, and most importantly, Tom.
[Disclaimers:]
This story contains -
TomTord, EddMatt, Paultryck, many OC's, deaths, mental and physical abuse, and emotional manipulation.
Kanda Kyoichi transmigrated to Konoha and became a temporary instructor at the Ninja Academy. Fortunately, he awakened the Mentor System.
By teaching others, he could earn rewards.
Thus began Kyoichi's career as a "teacher" in the ninja world.
Shisui: "Sensei's unique interpretation of the Will of Fire has given the Uchiha Clan a true sense of direction!"
Asuma: "The essence of the jade lies in protecting the people, with the advanced leading the way for the less experienced. Only then can Konoha become stronger!"
Kakashi: "He's my life mentor. He transformed Konoha!"
...
Years later, in the memoirs of Kyoichi, now the Hokage, he wrote:
"I honestly just wanted to be a life mentor!"