A letter suddenly arrived at Hiroaki's from his mother, Kyoko. The two had parted ways 15 years earlier and hadn't seen each other since. In the letter, Kyoko wrote that she wanted to see Hiroaki just once, to witness how much he had grown. Though filled with doubts, Hiroaki boarded a train bound for Matsumoto. During the journey, Kyoko gradually revealed the truth, deepening their bond. As they spent days together at a hot spring inn, the boundaries between mother and son slowly dissolved. Hiroaki confessed, "I was truly lonely all this time," and soon forbidden feelings began to stir between them.