L: The Wammy's House/One Day

L: The Wammy's House and L: One Day are two manga chapters that were released in L: FILE No. 15, a special book released in conjunction to the Japanese release of L: Change the WorLd. Although technically comprised of two chapters, the both of them combined contain a modest 12 pages.

L: The Wammy's House
L: The Wammy's House begins when Watari first brings L to the orphanage as a child. It shows the events leading L to become a detective, and is narrated by Watari.

Watari begins by saying that "L, a nameless orphan, was taken into the orphanage I had established. Before one hour had passed since he entered, L was already causing a disturbance."

L's first days at the orphanage are a little rocky, as L doesn't get along well with the other children. Soon after arriving at Wammy's House, Watari finds L in a play room with the other kids, however the children are on the floor seemingly injured. When Watari asks L what happened, L explains that the children yelled "A new face! Let's cuddle him!" and then attempted to "imploy violence" on him. L says that "they started it" and declares "I am justice!"

Watari explains that L hoarded the toys that he liked "because he was stronger", and that he often played alone. His abilities were clear even as a child. One day L tells Watari that he wants to play with puzzles and games that are harder. Watari gives L his own room to play in, and L says that having his own room is "nice". Three days later, L asks for a computer because "communication through a computer would give [him] power". From then on he almost always sat in front of the computer.

L began telling Watari how to invest in stock, leading Watari to multiply his fortune by twenty-thousand over the span of two years. Several years after that, L suddenly stated while reading a newspaper that "This serial murder case is more difficult than any puzzle or game." The case had no leads and Watari says that when L found the killer, L's eyes "were shining." It was at that moment that Watari found the path he would walk with L.

L: One Day
L: One Day depicts L's life as an adult. It shows him doing various activities. It begins with Watari saying, "One can say that L has no concept of time, nor does he have any internal clockwork.".

Watari brings tea to L, and tells him good morning. He tells L that he slept almost seventeen hours after one-hundred and two hours of no sleep, and that he should sleep more. L asks Watari if he can help him up, and it is revealed that L is actually sitting horizontally, with his chair laying on its side against the floor. Watari lifts the chair and turns it right side up.

Next, we see Watari helping L change his shirt. Watari explains that L cannot do it himself, but then corrects himself and says that it's really because "he never feels like doing it." Watari goes on to say that most of the time L is in his room sitting "in that position" without moving. However, there are times when he goes outside. Watari says that L "doesn't dislike amusement parks" and begins to name some other places that L visits, including a park, an art gallery and a music concert. As these places are named each panel on the page displays a picture of L attending them. Watari then states that most other time is spent thinking over things, or solving a case and eating sweets. Watari concludes that, "That is L."