Yuki was born when Naoko was 20 years old. - Her father disappeared, and Naoko raised her alone, despite the opposition of those around her. - Sometimes kind and sometimes strict, she raised Yuki as a mother and father. - As a result of his efforts, Yuki was able to successfully get a job and live in a dormitory. - Years have passed since then, and Yuki has had a long holiday and is returning home for the first time in a while, and Naoko takes him on a hot spring trip without bathing.