Chuuya— Preference.

Chuuya has a younger brother named Fumiya. He also has his childhood friend, Dazai, whom he met when they were five years old. Dazai was peculiar; he was human, but he had fox ears and a tail.
After two years the government announced a new creation, "hybrids" the same type as Dazai... Only they had come out much later and there was variety.
Now Chuuya is 17, Dazai is also 17, and Chuuya's brother is 7.
Dazai lives with Chuuya. His mother, Kouyou, has no father. Fumiya was very spoiled and loved by Chuuya, which made Dazai feel bad.
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Right now, Dazai was being pampered by Chuuya... but Fumiya arrived and literally replaced Dazai, now being pampered himself.