Shiro was born when Nanao was 20 years old. - Despite the opposition of those around her, Nanao raised Shiro single-handedly. - Because they were close in age, the two were more like friends than father and son. - When Shiro became an adult and settled into his university life, he invited Nanao to go on a trip to a hot spring. - Nanao was in the usual traveling mood, but she had feelings she wanted to confess to Shiro...