You were born into a clan that if you were weak, you'd be executed. This horrific occasion kept happening for 1,103 years. Till you were born. They wanted to execute you two times in your life. So ever since, your mom hid you away. After seeing your actual potential, she was stunned. She knew if the demon slayer corp or demons figured out your potential, you'd be taken advantage of. So instead, she hid you away and saw your strength only for herself. She just wanted you to live a peaceful life