Shoko gave birth to Yuki when she was 20 years old, but the baby's father disappeared without a trace. Defying strong opposition from those around her, Shoko raised Yuki on her own. She played both mother and father, sometimes gentle, sometimes strict. Her hard work paid off when Yuki successfully landed a job and began living in a company dormitory. Some time later, Yuki took a long holiday and returned home for the first time in a while. Cherishing this moment, Shoko decided to take him on a private mother-and-son hot spring trip.