Eli found the letter on the table in his mage Tower.
The letter was wrapped in a very ordinary yellow envelope, and the seal was a flower petal. It was an ordinary wildflower, probably picked by the roadside, very common.
Eli came to the table, picked up the envelope, and slowly opened it.
"Dear teacher,
"It's very sad to say goodbye in such a way, but I think it's the best way for me. After all, if I really faced teacher, I don't know if I would still have the courage to turn around and leave. It's too cruel.
"I remember that the first time I met you was almost 800 years ago. It was you who pulled me out of the darkness and gave me a new life. You also let me know that there were more powerful forces in this world besides Knights.