Comedy, Romance, Ecchi, Seinen, Slice of Life, Adult

When Haruma Kawagoe was a child, his mother had a miscarriage and wasn’t able to have any more children. Haruma prayed to God that his mother would get well and that he might still one day have the little sister that he’d been looking forward to having. One strange Christmas years later, “Santa” drives up on a hovering sleigh and delivers to Haruma a present -- inside is a young girl! Haruma finally has his little sister, who he names “Choko”. Choko does her best to be the perfect sister by consulting the guidebook she carries with her, and Haruma similarly does his best to adjust to being a reliable older brother. But when your little sister kisses you and walks around naked, adjusting isn’t easy at all!