It has been 2 years since Masashi Majikawa, a young widower with an 11-year-old son Atsurou, remarried Ikune, a young widow with an 11-year-old daughter Iona. They are a normal, harmonious family thanks to the children liking their new parents. To celebrate the anniversary, Ikuna and Iona planned a trip to hot springs, but the two of them other motives as well, and a private bath is essential to realising their vision.