I Have an Invincible Master

"Master, are you strong?" "Haha, it's not very strong. After all, the people in this world who can be killed as teachers haven't even been born yet!" "Then how can I practice to surpass Master?" "Haha, when the water flows upward, when the world is on fire, and the wind grows there, you will be able to surpass the master!" "..." I didn't expect that he should be a harmonious little old man. I didn't expect that he would be famous in the whole world as a top expert! This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.