|Japanese VA||Tōru Nara|
|English VA||Patrick Poole|
"Penal Code Section 361 Article 1, self-defense! Necessary actions taken in defense of a pressing and illegal threat are not punishable by law!" — Sōichi Natsume
Sōichi Natsume (夏目 総一 Natsume Sōichi) was the attorney of Kōsuke Kira. He later became a player in the live-action Btooom! game and affiliated himself with Kōsuke and Kōsuke's father Yoshihisa Kira. After a fall-out with the group, he allied himself with Masashi Miyamoto.
A bespectacled, middle-aged man, Sōichi has dark brown short hair parted to the side. He wears typical attorney attire: a white, buttoned-up shirt, with a shirt pocket; a black coat he carries; black pants, with black suspenders; and black dress shoes. A Btooom! player, Sōichi carries a bandolier on his waist and has a IC chip implanted in his left hand.
An attorney, Sōichi possesses a strong sense of justice. He is idealistic and optimistic. He believes that what society perceives as right should be accepted without question as well as for what is wrong.
Upon reappearing at Masashi's side, Sōichi's personality exhibited drastic changes. Although initially a pacifist, he became more acceptant of his situation. Additionally, he is unhesitant in attempting to kill others, justifying his actions as an act of self-defense. He has also developed a sadistic side, as observed when he began to kick Ryōta Sakamoto unnecessarily and allowing Masashi to torture Himiko. However, his actions were also influenced by his stimulant doses, which he obtained from Masashi in order to repress his fear.
- Kōsuke Kira — A client of Sōichi's who was charged with murders of three women and several thefts. Sōichi managed to convince the court to greatly reduce his sentence. On the island, Sōichi allied himself with Kōsuke and Kōsuke's father, Yoshihisa. Often, he would advise Kōsuke on morality as well as sympathize with Kōsuke's resentment toward Yoshihisa. He wanted Kōsuke to stand up for himself and said he would support him if he ever did. Shortly after Kōsuke killed Yoshihisa, Sōichi became disgusted with his behavior, prompting him to leave Kōsuke behind, breaking off their ties for good.
- Masashi Miyamoto — Some time after leaving Kōsuke behind, Sōichi allied himself with Masashi. In attribution, Sōichi was docile toward Masashi, even agreeing to assault other people, and had received stimulants from him in order to suppress his fear. Although Masashi didn't show much concern for Sōichi's well-being, Sōichi didn't seem to notice.
- Yoshihisa Kira — Father of Kōsuke, a client of Sōichi. Sōichi discouraged any pessimism from Yoshihisa as well as his abuse toward Kōsuke. However, it only continued until Yoshihisa began intimidating him when Sōichi questioned his selfishness. Although the two were not on good terms, Yoshihisa's death attributed to Sōichi's concept of "self-defense."
- Ryōta Sakamoto — Although he didn't know him personally, Sōichi looked down on Ryōta, mocked him, and labeled him a murderer since, assuming that the amount of bandoliers Ryōta had was the amount of people he had killed. In their second encounter, Ryōta killed Sōichi.
Before the events of the island, Sōichi represented Kōsuke as his attorney in a court case that charged Kōsuke with the murders of three women and several thefts. Out of sympathy toward the victims' family, the jury gave the maximum penalty to Kōsuke, but was later greatly reduced when Sōichi used the results of Kōsuke's psychological examination as grounds for his defense.
On the noon of the second day of the game, Sōichi witnesses Kōsuke killing frogs for pleasure. After the two meet, Sōichi discusses the morality to Kōsuke as they walk along the beach shore. He states there's a difference between killing for food and killing for pleasure. The two then notice a cargo plane overhead parachuting a supply package nearby. Kōsuke immediately decides to investigate, prompting Sōichi to stop him, suggesting that they go ahead with Kōsuke's father to be safe
As the three proceed toward the location, Yoshihisa states there being little hope even if they reach the location. Sōichi reassures him to be hopeful of a safe solution, prompting Yoshihisa blame their situation on his own son. Kōsuke grits his teeth in response, irritating Yoshihisa enough to kick him in the stomach. Sōichi stops Yoshihisa from going any further, insisting that violence does not solve anything. Annoyed, Yoshihisa proceeds ahead of the two. Sōichi, taking notice of Kōsuke's lack of protest, encourages him to stand up against his father, promising to protect him if he ever did so.
Once at the supply package's location, Sōichi notes that the supply package is caught in the tree. Yoshihisa then takes one of Kōsuke's implosion BIMs by force and attempts to install the BIM onto the tree. To his dismay, the BIM falls to the ground. Sōichi picks up the BIM and repeats Yoshihisa's actions, producing the same result. Sōichi concludes that only the owner can activate their BIMs. Yoshihisa then instructs Kōsuke to install his BIM onto the tree trunk. The implosion BIM activates and fells the tree and the supply package with it. Yoshihisa takes hold of the supply package and says to follow him for food. It is then that Sōichi realizes that Yoshihisa is claiming the supplies for himself.
Sōichi protests, advocating equal division of the supplies. Irritated, Yoshihisa states that the law has no effect on the island as the strong rule over the weak. Whilst the larger man intimidates the attorney, Kōsuke mutters of how horrible a person his father is. Yoshihisa then sexually abuses his son by grabbing in the area of the crotch, making an attempt to reaffirm his will over Kōsuke himself. Suddenly, Kōsuke installs a BIM onto Yoshihisa's shirt. Sōichi hastily instructs Yoshihisa to remove his shirt. Unfortunately, the BIM implodes, killing Yoshihisa. Kōsuke then approaches the attorney, expressing his gratitude toward him and states that Sōichi will definitely protect him again as he had done so before. This nauseates Sōichi. Sōichi then makes an outburst against Kōsuke, insulting him before leaving, cutting off all ties between them for good. As he does so, a sonar wave detects his presence.
Some time on the third day of game, Ryōta, whilst being chased by Masashi, briefly senses the presence of Sōichi with his radar (at the time the two had not personally met) and avoids him completely. After negotiations with Masashi fail, a timer BIM is cast near Ryōta, which then explodes as Ryōta evades. Afterward, it becomes apparent that Sōichi had thrown the BIM and that he is allied with Masashi. Ryōta is then knocked out by the butt of Masashi's knife. Shortly after, Sōichi, after checking Ryōta's bandoliers, notes of Ryōta's large amount of BIMs despite the latter's earlier pacifistic approach. He then kicks him in the stomach and mocks him, labeling him a murderer. Shortly after, he discusses the fate of the man with Masashi. While the attorney is busied with the topic, Ryōta uses Himiko's stun gun on him, incapacitating him momentarily. Ryōta escapes. After recovering, Sōichi apologizes to Masashi, claiming responsibility. Contrary to what Sōichi had assume, Masashi is not angered at all. This is when he reveals to Sōichi that not only was he planning on letting the man loose but that he is also not alone, which leads the two to track down Ryōta to his base.
This plan is later considered as a major success to the two, as not only had they successfully tracked Ryōta down to the whereabouts of where he and his allies were taking shelter in but also by obtaining their supplies and BIM, capturing Himiko, wounding Kiyoshi Taira, and assuming that Masashi killed Ryōta. The two are later seen taking shelter in the ruins of large building. With the success of the plan having given them supplies to consume upon, the two begin devouring both the food and water. Himiko begins to protest against such actions. Masashi flashes his knife over Himiko, with the intention of torturing her. While the man begins to do so, Sōichi comes over to observe.
Suddenly, a sonar wave is sent, picking up the presence of the three. Giving haste, Masashi calls a retreat as their location is now exposed. Himiko then sends out two sonar waves in response, which is then responded back to by two sonar waves in return by the unknown person. Sōichi questions whether this is a signal or not. It is then that Masashi realizes that Ryōta is not only dead but that he's attempting to rescue Himiko. Masashi then informs Sōichi of not only their opponent's identity but that they will be taking the offensive. They then eventually reach an intersection, to which they then form a plan: The two will split off in two different directions for an ambush. Sōichi will head toward the main entrance while Masashi to the left. Before they do, however, Sōichi receives more stimulants from Masashi as his fear is starting to come back to him. Afterward, Masashi then gives the attorney the following advice: "Since your BIM detonates after 10 seconds, set one's remaining time to 3 seconds."
Some time passes. A blast goes off. A sonar wave is sent. Footsteps are then heard from afar. Sōichi (off-screen) concludes that Ryōta couldn't have survived the blast and that his remains may be scattered about. Afterward, he heads toward Masashi's direction. As Sōichi does so, he is nearly killed by Masashi out of the assumption that he was not only dead but that Ryōta was the one nearing his location. The attorney falls backward. Masashi then demands to know what happened, to which Sōichi relays that he couldn't find Ryōta after using his BIM. The two then simultaneously send out sonar waves, but unknowingly cancel out each others' radar. Shortly after, they locate Ryōta with Himiko. Having realized the two are now together, Sōichi and Masashi split up once again for an ambush. As Sōichi heads off, he maniacally justifies that his actions are that of "self-defense."
The attorney soon encounters Ryōta. He then hurls a timer BIM toward his direction, missing the man. As Sōichi gives chase, he taunts Ryōta. Another BIM is thrown, exploding once more, but again, missing its target. As the smoke from the explosions rises, Sōichi stops for a moment to assess the situation. He then concludes that he must finish this battle with aggression if he doesn't want to be killed, just as Yoshihisa was. The attorney sends a sonar wave and manages to locate Ryōta. As Sōichi rushes over, he spots Ryōta at a dead-end, then assumes victory. However, Ryōta's ploy is soon revealed. As Sōichi rushes toward Ryōta's location, he catches a glimpse of a cracker BIM at him. As Sōichi is momentarily confused, the BIM explodes, killing him.
Equipment and skills
- Sōichi exploited the timer BIM's ability to stop its timer at any desired number. He would set his BIMs to stop at "3" in order to give his BIMs a shorter countdown when activated.
- Observed amount used: 4.
- He used one during his first encounter with Ryōta and three during his second encounter with Ryōta, which was all on the third day.
- His BIMs were obtained by Ryōta and Himiko at post-death.
- Btooom! manga, chapter 7, page 14
- Btooom! manga, chapter 25, page 21
- Btooom! manga; Chapter 28, page 8
- Btooom! manga: chapter 8 and anime: Episode 4
- Btooom! manga: chapter 8 and anime: Episode 4
- Btooom! manga: chapter 29, pages 15-16 and anime: Episode 7, Virtual Bride