Miss Kobayashi's Dragon Maid Vol. 16 (manga)

The “Arena of Trials,” a tournament held by the god Loki, begins in the other world. As dragons test their strength against each other, Loki amuses himself by forcing the human Miss Kobayashi to compete, and pitting Tohru against Fafnir just to see what happens. But when some of his toys refuse to play along, Loki grows increasingly annoyed... As dragons who despise humans battle it out, Tohru’s feelings for Miss Kobayashi will overflow into the arena!