Crid was born in a small village of Atop where peace would relax at. With there being no desire for war and destruction it was a perfect place to live. At age of 3, Crid spend his life as a scared caring child that would always spend his time looking at a stream of water flow by next to his house till night fall. When danger hit in town he jump into action and try to save anyone he can but due to his lack of strength he would always lose. At age of 4 a monster known as a Vindorn attack the village of Atop and murder everyone in it including his parents. With him as a survivor a Demon Hunter name Shino found him scared and alone and took him in his care.
At age 7 was when he was given his first mission of transporting a monster known as a Giant. Was requested by the Blade Knights him and Shino took on this task and with being half way to the spot needed they were ambushed by a group of monster wishing to free the Giant. After the Monster's success the Blade Knights ran away from the ground leaving the Demon Hunters to fight the problem them self. After the battle Shino met his death defending Crid from the Giant's attack when Crid went in rage and killed every monster in his path. Leaving no monster alive he experience the taste of blood and enjoyed every minute of the monster's death. Once return the Blade Knights claimed the members of the Demon Hunters as cowards who fled the battle field wail the Blade Knight's fought the Monsters. With a fight in court between the honor of the Demon Hunters and the Blade Knights to prevent war from happening the court agree with the Blade Knight and put Crid and others from the team in shame.
Rage and hate flowed in the boy towards the Blade Knight's leader of the 4th squad he would not give up that easy in the battle. One night making his attempt at revenge he head over to there base alone and killed every Blade Knights in the 4th squad known as the strongest squad in the Blade Knight's court. With the leader of the 4th squad still alive she claim against Crid as a traitor and dare to declare war. Crid lost his rights as a Demon Hunter and had to go to training given the name "Blood Slayer" a human who is a monster. Being scared by every member in the training ground not knowing he already was a high rank Demon Hunter everyone would look down on him and see him as a monster treating him like trash.
Treated so he lost all kindness in his heart in defending people and just ignore any battle happening with no spirit for fighting. All his hope has shatter and he just stop caring for everyone and respected himself only. Keeping his name he became a fear to the school when he walks down the field. No one would get near him but a girl name Lizzy who is a new member to the training ground and thick headed would always spend her time next to him. No matter to how much he threaten her to leave she would never give up on him and comfort his broken heart. After passing the Training ground he was given rank as a leader to the 5th class of the Demon Hunter and continue on his travel alone as the Blood Slayer or a Monster with a sword. He has no heart anymore for humans that made him suffer as much as the Monsters have.