Akino Ryuuya

The main protagonist. A schoolboy who is faithful to his own desire. He has an optimistic attitude. He is also a huge fan of animal fetishism. He is good at housework due to his parents being away often, and Miya is useless at them.
He affectionately refer to Miya as his 'No-good' sister, but he is fond of her and lends a hand whenever she is in trouble.
Natsuki is a friend of his sister, so they interact often.
Mari is a close friend of his.
Umi is like a little sister to him.