When first introduced, Shin is portrayed as a carefree and charismatic youth. As the series progresses, the darker aspects of Shin's character come to light. In addition to having a severe sister complex, he is exceedingly possessive and violent.
Shin is defensive of Maya due to the restraint her mere presence puts on his mad frenzy. Given his insanity Shin's behavior is highly erratic, making a summation of his personality difficult. He is also a skilled martial artist as he was trained by Dogen Takayanagi, and actually managed to "steal" the Takayanagi family secret technique. Up until his death Shin was the President of the enforcement group, and the 2nd ranked fighter in the school only because he didn't actually fight in the election tournament that year. He was later beaten by Bunshichi, the 1st ranked fighter in a street fight, although he could easily kill him if he activated his Red Feather power the "Dragon's Eye", but that would also means he would go on a rampage and kill every surrounding person there, so he decided not to do it.
Despite his insanity, Shin seems to play a mentor-like role to several characters in the series. He has a massive influence on the majority of the characters in some way, even appearing to some when they need guidance. Overall a good chunk of the story is based around the possibility of a repeat of history, many fear an incident like what happened to Shin will be repeated.
Shin seems to know he's crazy, seemingly indicating he wants to be taken down if he goes too crazy. He seems almost spiteful of his own power, as he doesn't understand why he was given a "completely worthless power". Despite this, he does seem to find it funny in his own twisted way.
Anime and Manga
Shin awakened his Dragon's Eyes as a child when Maya Natsume allowed him to touch Reiki, however he was unable to control it. Kaima Natsume (Shin's father) tried to hide him from the other families of the Takayangai flying Phoenix because he was afraid they would kill Shin and the whole family out of fear that he couldn't handle it. Shin was locked up in an underground dungeon, only visited by Maya. Shin's Dragon's Eyes allowed him to see dead spirits that were in the dungeon. Kaima's plan actually drove Shin more insane as opposed to helping. As a result of Maya being the only one to visit him or bring him food, Shin became very attached to her.
When he learned that his father was planning on sending him away, thus separating him from Maya, Shin broke free and used the Reiki to kill his parents. From then on Shin often carried the Reiki as opposed to Maya. Shin caught the attention of Dogen Takayanagi who trained Shin in the martial arts, for purposes other than what he revealed. Mana Kuzunoha was assigned to be Shin's girlfriend, in order to watch over him. However, Mana fell in love with Shin for real. Shin with Mana's help formed the Team KATANA, and entered Toudou academy as one of the top fighters in the school. Because Shin never actually fought in the election tournament, his best friend Bunshichi Tawara was ranked number 1 and Shin was ranked number 2, but he still became the executive council president.
As Maya entered Toudou, she started to get angry because her brother was constantly interfering in her fights. She started to take away his "power" by attacking the members of his gang, she was referred to as the "KATANA hunter". At same time Mitsuomi Takayanagi met Shin and was taken under his wing, later establishing a relationship with Maya. Mitsuomi also had an affair with Mana, though he did not really understand why she was interested in him. He also noticed Shin had a bad habit of going overboard by nearly killing anyone he fought. With the KATANA hunter getting more and more bold, Shin started to act strange. Mana provided Mitsuomi with a video showing Shin slaughtering people for a distraction with Reiki. Even beating up and nearly killing the members of his own gang, so they wouldn't go for revenge on Maya. Bunshichi went to beat some sense into Shin, discovering Reiki was somehow behind Shins strange actions. After Shin's defeat by Bunshichi, with Reiki being taken away from him, he seemed to return to normal. Shin's eye was injured in the fight, so he wore an eyepatch for a while.
After getting out of the hospital Shin decides to hold one final KATANA meeting, to which only Mitsuomi is invited. All the other members quit, except Bunshichi. Bunshichi did not like not getting invited, but Shin explained he did not invite him because thanks to a car smashing his bike, Bunshichi had no motorcycle. On top of that with Bunshichi's legs still injured he could even ride with someone else. Regardless Bunshichi obtains a scooter of some sort to try to attend anyway, but is ditched and spends all night looking for them. This final meeting consisted of a motorcycle race between Mitsuomi and Shin. While going over 150 km/h Shin starts to ask Mitsuomi to take him down if he ever loses control, and drowns in his power again. Mitsuomi does not answer directly, simply stating its time that he takes the lead, and tries to pass Shin. This is one of the many instances where Shin seems to indicate he wants to be taken down by Mitsuomi. Ever since he killed his parents Shin had seen the figure that would take him down, eventually realizing it was Mitsuomi. During a conversation with the ghosts of his parents, Shin seemed to indicate Mitsuomi was all his power coming back at him to defeat him.
As the schools annual tournament approached, Shin wanted to participate. He created the Juken club consisting of the few remaining KATANA members so they could compete. As only Shin, Mitsuomi, and Bunshichi remained and 5 members are necessary they were hard pressed to find other members. Mitsuomi convinces Maya to join, and later Maya finds their fifth member. Feeling so confident the 4 of them could handle any opponent Maya grabs someone from her class with little to no fighting ability, Kagesada Sugano, nicknamed by a teacher: Asshat (in the anime he is called Scum). As the tournament begins, Mitsuomi and Maya are handling most of the fights pretty well. Shin is upset by the new teamwork of Mitsuomi and Maya, feeling Mitsuomi is replacing him, Bunshichi convinces him to let it go. As the finals approach Dogen calls Shin out and tries to return Reiki to him, Shin refuses. Dogen wants to turn Mitsuomi into the perfect warrior, and believes he needs some evil to fight to become such. Dogen wants Shin to be this evil. Since his first idea failed, Dogen has Fu Chi'en attack Maya to drive Shin crazy.
As Shin shows up late for a match his opponent opens the door for him to reveal the beaten and barely clothed Maya. Shin's Dragon's Eyes actually activate Reiki even though he is not in possession of it. He kills or nearly kills his opponent and Fu Chien's men. Mana runs off to find Mitsuomi, believing only he could stop Shin in this state. Fu Chi'en feels confident he can take a kid who can't control his power, and attacks Shin. Shin ends up ripping Fu Chi'en's hands off at the wrist, and beating him unconscious. As Shin starts to attack the innocent Emi Isuzu, who was actually trying to help, Maya calls out to him calming him down. Just then Mitsuomi busts in and rushes Shin, Maya stops him by calling for him. Jealous Shin's Dragon Eyes activate again and he blasts Mitsuomi with a large quantity of KI. Later in the hospital, Shin apologizes to Mitsuomi claiming he turned with his eyepatch side and did not see who it was until it was too late. Both Mitsuomi and Maya know this is a lie, Maya starts to yell at him, but Mitsuomi just agrees and leaves. Only later did he realize the severity of the injuries, and the effect they would have. At this point Shin has been fully driven insane. He has decided to take overprotection to the extreme, and kill anyone who gets near Maya. Using his Dragon's Eyes Shin predicts who could possibly be a threat and takes them out. Fu Chi'en awakens in the hospital and decides to get revenge on Shin, he gets blades attached to his wrists and plans to go after Maya to hurt Shin the most. As he leaves the hospital room he sees a man in a hood, it is Shin. He beats down Fu Chi'en and cuts his face off (in the anime his face looks as it has been burned off). He then goes outside and tells Maya his plan to kill anyone near her. As Mitsuomi arrives one day for Maya, she seems really freaked out and blows him off, telling him not to come back. Mitsuomi sees a reflection in her eye, Shin is behind him with a knife. He figures out what is going on and promises to get stronger and take down Shin to free Maya. Two months later, Shin insists on a Juken club photo, almost strangely out of character as he did not want anyone around Maya. Shin challenges Mitsuomi to a fight to determine the executive council president. It really appears Shin knew he had lost it and wanted Mitsuomi to take him down like he mentioned during their motorcycle race. Mitsuomi dominates this fight, but Shin fights without his Dragon's Eyes. Mana says this is because he is trying to fight his cursed power not Mitsuomi. Shin however plans to take Mitsuomi out with him, as he receives a hit he grabs Mitsuomi and uses his elbow to try to smash Mitsuomi on the floor in a way that would break his neck. He fails, and it seems that Mitsuomi defeats him, as he goes for another punch Mana jumps in the way. Reiki activates in Dogen office as Shin succumbs to his power. Shin steals the Takayanagi family secret technique, the Forged Iron Needle Attack, and blasts through Mana and hits Mitsuomi. He then pummels Mitsuomi, as well as everyone else in the room. After he returns to normal he walks over to the dying Mana, with her help he uses one of her acupuncture needles to stab himself in the ear killing himself so they could die together. This is an unusual part of this series, Mitsuomi claims credit for killing Shin during the bowling alley incident, Maya seems to blame him for Shin's death. Shin killed himself, Mitsuomi was trying to save Maya, as she was over protected by Shin. Many things are still unknown about Shin's death.
It was later revealed by Mitsuomi that the reason Shin chose him and not Bunshichi to take him down was because of Bushichi's compassion.
Throughout the series Shin's ghost seems to make appearances to guide people, and make suggestions. So far his ghost has appeared in the anime to take Reiki away from his other sister Aya Natsume, and inform her that it would eventually destroy her like it did him if she kept it. Later in the manga he also appears to Bunshichi. Bunshichi talks to Shin's picture asking if its fate or a joke of Shin's that people seem to be repeating history. Shin's spirit shows up and asks him why he does not just smash it all up with those two arms he's so proud of. He later appears to provide motivation to Maya Natsume, even slashing at her with Reiki to force her into action. He also reappears to her at the last chapter of the manga once more, listening to her confession of why she was going to die for the future that she was going to leave for others. He seems resigned to what she says.
Unlike his chaotic state when he was alive due to the Reiki, Shin's ghost is calmer and more at ease as he doesn't seem to harbor the same resentments and insanity as he did when he was alive. The first time he appears to Maya as a ghost he is even able to discuss her desire to be with Mistuomi in stride showing that he has moved on from his jealousy and insecurity. He also appeared to Mitsuomi and teases him during his fight with Bunshichi jokingly stating that he was the only one who wanted to see him dead.
Shin has the power of the Dragon's Eye, which synchronizes with the spirits of all things, thus it gives Shin a type of prescience that allowed him to see anywhere past, present, possible futures, as well as seeing and hearing the dead. He gained this power as a child, and it was far too much for him. As with all Dragon's Gate related powers, losing to your Dragon and becoming insane and violent is a huge risk. Shin lost leading to his erratic and violent behavior. His power played a key role in his insanity, the other part was due to his father.
When Maya asks why he didn't just predict certain occurrences, Shin compares his power to rain. All the rain drops hit a predetermined place, based on wind and such. They congregate together to and flow, eventually making a stream, according to Shin that is fate. He basically says he can hear the rain, but he can't understand the significance of every drop. Basically indicating his Dragon's Eye will only show him bits and pieces of possible futures, and he doesn't have the ability to piece together the whole picture. This makes the power worthless in his opinion.
Reiki is an evil ceremonial Nodachi that is the heirloom of the Natsume family. It allows those with powers to use them more freely, but this is risky as the more frequently a person uses their power and the longer they sustain it, the more likely they will lose to their Dragon. As Maya does not have any powers or had the Amaterasu Dragon's Gate, Shin's father entrusted Reiki to her under orders to keep it away from Shin. She failed in this, and Reiki is largely blamed for the events leading to Shin's death. Shin carried this blade with him the majority of the time, frequently using it to slaughter innocents for a distraction. He developed a good enough connection with the blade that he could activate it without even being in the same room with it.
- Uraate (裏当て; lit. "Backing", CMX Translation: "Reverse Striking"): This is fulcrum-based transference skill, an example of KI transmission that teaches one to shift the point and force of impact by striking the dead center of an object. At expert-levels, a practitioner can transmit the force of impact wherever they please, as long as a medium exists to transmit their power through. This technique forms the basis for most KI-based techniques used throughout the series.
- Ryukei Qigong Tashinkō (龍形気功鍛針功; lit. "Dragon Qi, Forged Iron Needle"): Considered the greatest of secrets within the Takayanagi clan, passed down for generations. Shin adapted this technique while in the service of Dogen Takayanagi. It is a technique which uses the fulcrum-based transference skill of "reverse striking" to transmit the user's power through the air. This is achieved by collecting the rotational force of one's motion until it forms unto a needle, forged by their own KI. At that point, that collected atmospheric force would then be directed from the circular motion into a straight line (via punch), where it is sent barreling into the target. Shin would inevitably teach this technique to his sister, Maya.
- Tetsushikō (鉄指功; lit. Iron Finger): This is a particularly lethal technique which uses the finger to punch through muscle and puncture internal organs, particularly the liver.
- The name Shin means "prudent, careful" (慎).
- Shin's surname Natsume means "jujube" (棗).
- Ziziphus jujuba, commonly called jujube, red date, Chinese date, is a species of Ziziphus in the buckthorn family.