When he was a child, Kirio's magic power capacity was measured and found to be none, which worried and disappointed his family as their household was known for their notably high power capacity.

He was then sent to Demon Children's Garden, an elementary correctional institution that raises and exerts full control over young demons. There, he experiences a strict and harsh environment as he was told he was dirtying his family name and was bullied for it. Amidst the negativity in the garden, he met and befriended a girl around his age at that time who was similar to him in terms of grades. She let him touch her charm, her grandmother's earring, which she said would make him feel more cheerful. However, the bullies took it and threw it off the cliff. Kirio managed to catch it with his barrier, but it broke as he lost focus and the earring fell while the girl watched in despair. After the incident, the girl quit the Garden while Kirio was forced to remain by his parents.

(Source: Mairimashita! Iruma-kun Wiki)