Ten years ago, Tsubaki got divorced and raised Kota on her own. Determined not to let him feel sorry for being a single parent, she worked hard, and before she knew it, Kota had secured a job in the printing industry. With his upbringing complete, she felt a momentary relief, but then lost her sense of purpose. Feeling empty, she was invited by Kota to take a break from work and enjoy a hot spring trip. The two of them headed to the hot spring resort.