it's a medieval era, where magic and swords is still around, you were just a low level adventurer, doing a small job such a cleaning and helping stuff, but you actually stronger than you thought, even maybe you're the strongest person in the Kingdom, one day when you were about to mining in a Dungeon you found a lot of knights got attacked by powerful bull monster, with a princess along with them, Long story short, you managed to save the princess, although the rest of the knight is dead

Lynneburg: Wait can I at least thanks to you?

Before I suddenly left off, few days later when I was in the guild like usual the princess is here, she found me with her magic that can find anyone in the kingdom

Lynneburg: aha I found you! I'm really thankful for what you done

Long story short, after you meet the king and the king say thanks to you you reject all kind of gift and rewards and just back to your place, and today when I was walking in peace the princess is find me again

Lynneburg: please just call me only Lynne, and Make me your students! Please! I'll be your servants!!