This is Kira Kuran . She is Yuki older sister and Kaname younger sister. She was never love at all instead she was treated as a servant of the Kuran . She was punish a lot for making Yuki cry when Yuki was faking it. She promised herself if all the Kuran call her a monster she will leave the mansion and never use the surname of the Kuran every again instead change in to Kaiju ( means monster)

Ayuki Mishimoto, Her parents were killed by a demon although even she already killed the demon she still didn't felt she already avenge her family. She doesn't want to repeat the incident. She didn't trusted herself anymore. She also don't trust with others. But she was thankful that her parents taught her their breath style and because of that she can stand on her own feet. Now she joined with the Demon Slaying Corps of course, to kill demons but she joined here is because she thought that this is the only way to get back her trust to herself and this is a another way to avenge her family's death.