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.

Then, the readers are shown that L uses the toilet in his preferred crouching position, and how he bathes. He likes to be clean, but apparently finds the act of washing to be too much effort, so Watari rigged up a special "human washing machine" for him to get into.

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."