The father is kind of pathetic, but at least he somewhat cares. It could be worse. Kids probably stay out later as they get older, but Sei doesn't usually do that. If your kid who doesn't usually stay out late, is missing for a day without any notice, you should be worried. Although, it could be the mom's doing. She's really manipulative. She could've prevented him by going out somehow, like, "watch the house incase he comes back"