Each chapter of this article is an independent short story. The entire series is about the story of Chong Zhai, the couple. The general background is: Okita Souji and Saito Ichi are reborn in the modern era with their past memories. Okita studied at the University of Tokyo School of Medicine and became a cardiothoracic surgeon, while Saito worked as a police officer in the Tokyo Metropolitan Police Department's Investigation Section 4, and the two lived together.