Suddenly, a mysterious woman named Sana with a scar on her back appears before Masako. Sana once made a contract with her employer as a ninja in the Warring States Period, and has lived her life without disobeying his orders. When Masako learns that Sana is a lifelong loner, she decides to keep her at home over the objections of her daughter-in-law, Kyoko. One day, while Masako, Sana, and Matsuda are gathering at Mitsuko's "Tenshukaku" restaurant, Masako's best friend Yayoi comes to them and asks them if they can help her.