Kujo Karuna manga
In the center of the land lies the human kingdom of Radiata and surrounding it are the lands of fairies, elves and goblins. The relationships between the two species were never good but things got worse after the attack of the dragons. Today is the Knighthood entrance exam for Ridley Timberlake and she has been training for this moment her entire life. Winning the tournament today means she will be initiated into the knighthood. Her first round is against a boy her age named Jack Lassel and she defeats him with ease. She fights her way to the finals where she becomes the champion and a knight only to find out that Jack, who is the son of the legendary dragon slayer, was also inducted.
From Shinnen: Naraka High School is a seemingly normal school. However, unknown to the public is the cruel truth of what really goes on in the school's halls. Rather than studying, students are forced to struggle for their very survival. And the strong bonds of friendship may be the only difference between life and death.