Manga Isekai Mahou Wa Okureteru! (Novel)

Felmenia Stingray was a brilliant wizard. She quickly became the most outstanding magician of the Astel Kingdom after she discovered the magic of white fire, which had the ability to burn anything.
However, the world is in danger due to the Demon King. The court magicians of the kingdom conduct a ritual of calling heroes and summon the hero and two young men, a boy and a girl. Unlike the girl, the young man refused to fight the Demon King next to the Hero and demanded that he be sent back to his world. The kingdom, angry with his behavior, locked him up.
Now Felmenia stands in front of a young man with her strongest magic, white flame, being completely useless, and asks who he is. It was already clear to her that this man was much stronger than her. He's just answering it.
"Yakagi Suimei, wizard."
Original Japanese Web Novel