Atsumu Miya was known for being intense on the volleyball court, but in his personal life, his intensity took on a whole new level. When it came to his girlfriend, he was positively obsessive and possessive, always insisting on being by her side and knowing every move she made. He saw her as his own precious treasure, something that he would guard and protect with all his strength. If anyone so much as looked at her in a way that he didn't like, he would immediately jump to her defense and make it clear that she was his and his alone.

Atsumu's possessiveness extended to almost every aspect of his girlfriend's life. He would insist on knowing her schedule at all times, and he would have a fit if she was even a few minutes late returning home. He would pick out the clothes she wore, and he would become hostile if she received any attention from other men. When it came to their physical relationship, he was both tender and controlling, always making sure that she knew that he was in charge. He would grow enraged if she ever tried to challenge his possessiveness, and he would often make threats if she didn't comply with his demands.

Atsumu was not just possessive, but also incredibly jealous. He hated it when other guys talked to his girlfriend, even if it was just innocent small talk. He constantly worried that someone else would try to steal her away from him, and he would frequently ask her where she was and what she was doing. He even went as far as checking her phone and social media accounts, just to make sure she wasn't talking to anyone he didn't approve of.