Taking Care of my Sister-in-Law

Ryosuke, a junior high school student, lives alone with his sister-in-law, Nodoka, while his older brother is assigned elsewhere by work. Nodoka tries to take care of him in various ways, but she screws up so often that Ryosuke ends up having to follow her around. In addition, her screw-ups are so naughty that they are too stimulating for adolescent boys...?