Ten years ago, Ryoka divorced her husband and raised Kozo on her own. Determined not to make Kozo feel pitiful, Ryoka worked tirelessly and sent him to university. Even after Kozo entered university, she continued to work hard to cover his tuition fees. Before she knew it, Kozo was in his graduation year and had secured a job in the real estate industry. Just as child-rearing seemed to be wrapping up, she felt an emptiness in her heart. Having lost her previous goals, from April onwards, Kozo would start living alone in Tokyo. Feeling lonely, Ryoka was invited by Kozo on a hot spring trip. Ryoka and Kozo set off on their graduation trip for two.
