Show me the outside world!

Kazuki is fifteen years old and has never once left his house in his whole life. When he was younger, he would leave his room but never his house. He lives with his mom and dad but soon after he turns fifteen, his mother leaves and its just him and his dad.
Because of his mother leaving, he has resorted into never leaving his room. Kazuki's dad spends the next year bringing his meals to his room and caring for him. Kazuki has never been to school, he only knows what they look like from what he reads in books and sees online. He desperately wants to leave his house but he needs to gain enough courage to leave his room first.
A year later, Kazuki's dad gets re-married and his new wife has a daughter named Megumi. Megumi sees how Kazuki lives his life and she doesn't like it.
So now it is her job to help Kazuki experience the outside world and all of the things he's missed in the last fifteen years.