The book, written by Isin Nishio and titled Death Note: The Other Notebook, is a prequel to the original Death Note manga, a story that takes place before the events of the main plot. In the book, Mello talks about L's first meeting with Naomi Misora in Los Angeles while solving the BB Serial Killer case, which is briefly discussed in the second volume of the manga. The author also talks about how L works. The book also describes Watari's orphanage, and how the entire system of geniuses such as L, Mello and Nia worked.