“If only I could see the death of the world.”
Beyond Birthday (ビヨンド=バースデイ, Biyondo Bāsudei) was the second child taken in at Wammy's House, in an attempt to create a successor for L, and the serial killer behind the Los Angeles BB Murder Case. Beyond Birthday has never appeared in the manga, anime, or film series to date, but the Los Angeles: BB Murder Case was briefly alluded to in both manga and anime.
Beyond Birthday appears only in the novel Death Note: Another Note - The Los Angeles BB Murder Cases.
The novel is narrated by Mello, who says that he is only telling the story in order to flaunt his greater knowledge of L over Near. Mello decides that Near might not be the only person to read the book, so he should make it more interesting. While narrating, Mello uses different techniques: he begins as a typical narrator, but drops it to acquire a way of speech that is usually associated with a live storytelling. The novel also switches from Mello's view and opinions to Naomi's point of view.
Throughout the novel, the reader is initially unaware that Rue Ryuzaki, whom Naomi Misora is suspicious of, is Beyond Birthday. Readers are led to believe that he is L in person. This is because of his mannerisms and description (black hair, dark bags beneath the eyes, bad posture, love for sweets, and sitting position). It is in fact Beyond pretending to be L, using his acting skills to pass as a copy of the L he possibly knew or heard about. It is unknown if he has ever seen L in person. The undisguised Beyond Birthday is mentioned by Mello at points in the novel.
Beyond is described as a young man with black hair and shadows under his eyes. He wears long-sleeved white shirt and faded jeans. He is thin and fairly tall, but always walks hunched over. Much like L, Beyond often sits with his knees pulled up against his chest.
However, he does not actually look like this. Beyond Birthday was said to have worn many layers of make-up in order to disguise himself.
Little is known about Beyond, though he and A were the first two children in line to succeed L. The pressure of Wammy's House proved to be too great for A, which caused A to commit suicide, while B left Wammy's House at some unknown point.
Throughout the novel, Beyond imitates L. Given that, it is unknown what actions are a charade, and what actions are a genuine trait of his personality. Beyond is once seen eating strawberry jam out of a jar with his hands. He appears to crave jam, as he has multiple jars of it in a victim's fridge. He also has a habit of crawling around in all fours and biting on his thumbnail.
Although mentioned only once in the book, it is also implied that Beyond practices laughing quite often. Also, it is interesting to note that his laughter is referred to by Mello as a "Shinigami's laugh."
Beyond was "born" with Shinigami Eyes, which allowed him to see and know when exactly people around him would die, as well as knowing their full names. He uses this ability to pick his victims and kill them when they would have been destined to die. It is unknown how he could have possibly been "born" with the eyes, though Mello wonders if a Shinigami dropped its eyeballs to Earth (instead of a Death Note).
- Note: The events from this Death Note novel occur before the storyline of both the manga and anime.
Beyond's whereabouts remained unknown from May 2002 to the beginning of the story, L having tracked cases around the world to search for him. Beyond came up with a plan to surpass L, as the "World's Greatest Criminal", giving L a case that he hoped L would be unable to solve.
On August 22nd, Naomi arrives at the location where the next BB murder will be committed, and comes to realize that Rue Ryuzaki, the mysterious private investigator she has been working with, isn't what he seems. After figuring out several clues, she finds that Ryuzaki is in fact Beyond Birthday, and that the final murder is actually his attempted suicide. She manages to stop Beyond from burning himself to death, and arrests him.
Years after his arrest, it is stated that on January 21, 2004, Beyond Birthday died of a mysterious heart attack.
Beyond Birthday's first known victim was the freelance writer Believe Bridesmaid, whom he killed July 31st, 2002, after drugging him and then choking him with a rope. Four Wara Ningyo (straw dolls) were left at the crime scene, and in post-mortem mutilation, Bridesmaid's chest was slashed several times; the killer also took the time to re-dress him. When looking at the autopsy photos, Naomi Misora found that the wounds were made to resemble letters (in actuality, a Roman numeral code spelling out the name of the next victim).
The second murder happened four days later, on August 4th. The victim, Quarter Queen (a 13-year-old girl), was also drugged before her death, the cause of which was blunt force trauma to her skull. Her eyes were also crushed in further post-mortem mutilation. Three Wara Ningyo were left at the scene of the crime.
The third killing happened nine days after Quarter Queen's murder. Backyard Bottomslash was a 28-year-old bank worker who had also been drugged before her death, though her age fell in-between those of the previous two victims (44 and 13). This happened when Beyond Birthday wanted to find out if a human can die of an internal hemorrhage without rupturing any organs. Beyond Birthday conducted this experiment by drugging and then beating Backyard Bottomslash's left arm without breaking the skin. When this did not work, her death was caused by loss of blood, with her right leg and left arm cut off. The right leg was discovered in the bathtub later. The left arm was taken by Beyond Birthday. Two Wara Ningyo were found nailed to the walls in a similar manner to the other two cases.
Beyond Birthday's final victim was himself, or rather, his fake person, "Rue Ryuzaki". By killing himself, he hoped to leave the case unsolvable. Beyond sets himself on fire in an attempt to kill himself, but his plan is thwarted by Naomi Misora, who sets out the fire before he dies.
Due to his resemblance to L, it is unknown if the artwork featured in Another Note is Beyond Birthday or L. Some fans believe it to be L, especially since he does not have red eyes, which the fans have begun to connect with Shinigami Eyes. However, it was mentioned in the manga that it is impossible for a human to see if another human has "The Eyes" or not, making Shinigami Eyes appear normal.
Others have pointed out that it is unlikely that there would be two protagonists in the artwork, as opposed to the protagonist as well as the antagonist. In addition to that, there is a distinguishable "B" in between the two characters, implying that the character may very well in fact be Beyond Birthday. However, there is no way of knowing until it is either confirmed or denied by Nisio Isin.
- Beyond mentions that he was a fan of the manga Akazukin Chacha when he was younger.
- In the movie L: Change the WorLd, when L is on his laptop and sending the message that Watari is dead to the members of Wammy's House, the letter B is seen on L's mailing list. It is currently unknown if this was Beyond or not.
- Though his alias "りゅうざき ルエ" actually translates to "Roet Ryuzaki" in English, the romaji "ryū zaki rue" was used for his alias in the English adaptation of the novel instead. 
- (to Naomi Misora) “I feel the word "private" carries with it an excess of neurotic egotism...you might say I am an unprivate detective-a detective without an ego.”
- “Ryuzaki: Don't worry. I'm a top.
- Naomi: A top?
- Ryuzaki: An aggressive top... I have never once been submissive. One of the few things I can boast about. I have never even been submissive to a traffic signal.
- Naomi: You really should.
- Ryuzaki: Never (p 82).”
- “If L's a genius, then B's an extreme genius. If L's a freak, then B's an extreme freak (p 96).”
- (to Naomi Misora) “So far this was merely a detective war with the killer, but from here on our lives are on the line. You should be ready for anything, Misora.”
- (Naomi Misora walks into the room Backyard Bottomslash was murdered and sees Ryuzaki lying still on the ground) “Naomi: Um, Ryuzaki?
- Ryuzaki: I'm a corpse.
- Naomi: Hunh?
- Ryuzaki: I have become a corpse. I cannot answer you. I am dead (118).”