15 years ago, Emiko divorced her husband and raised Tatsuya alone. Not wanting to make him feel pitiful because they were a single-parent household, Emiko worked tirelessly. Tatsuya safely graduated from university. After graduation, he started working at a beverage company and lived modest but happy days. During this time, Emiko began complaining about her health. Wanting her to rest since she had been pushing herself for his sake, Tatsuya invited her to a hot spring.
