Shu Ouma is one of the main protagonists of Guilty Crown, whose right hand holds a special power called the Power of Kings, given to him by the Void Genome. He attends Tennouzu First High School in class 2-A and is a member of the modern motion picture research club.
He is usually seen wearing his school uniform. He has brown hair with a light blond streak on the left side and brown eyes. For his time with the Undertakers, he wore their standard uniform. Since he acted as the King of his school, he wore a green coat, a scarf, a white t-shirt, black pants, and a chain. After episode 17 he lost his right arm, which he replaced with his void in episode 19. Also episode 19, he gain the Apocalypse Virus on the right side of his face.
The initial statement was: "Shu was an unsociable 17 year old who tended to stay out of peoples way, forming quasi-friendships with others, but nothing more significant. However, this changes when he meets a girl named Inori Yuzuriha. From that moment on, he gains the responsibility of one with "The Power of Kings," and he must learn to overcome his own weaknesses and form lasting bonds with his friends and allies."
From the first episode, he thinks very lowly of himself, purposefully distancing himself from others and remaining, for the most part, aloof. His turning point was the decision to save Inori from on oncoming Endlave, at great personal risk. It was this moment when he gained "The Power of Kings". In later episodes, with his new allies and elevated responsibilities, Shu has developed into a much more brave and sociable person, something noticed by his friend Hare and others. His new-found bravery solidifies when wielding Voids in battle, becoming a determined, powerful and expert fighter. Very early in the series, Shu gains feelings for Inori, which many people easily see and frequently attempt to use in their favor. He is disheartened when any male character gets too close to Inori, and is heartbroken when she has to leave in episode 10.
Following Gai's death, Tokyo goes into lockdown following the second outbreak of the Apocalypse Virus, Tennouzu becomes a safe haven for the students. Shu becomes the student's de facto guardian when the district Tennouzu is in is determined dead by the Japanese Government. His responsibilities culminate when Arisa, the current class president, is deemed unfit to continue ruling the student body, and Shu replaces her at the behest of the students, who are now aware of his power. His early ruling days were kind and gentle, though it was pock-marked with incriminating and ascerbic rumours surrounding him, as well as rising bitter feelings amongst some of the student body. When they acquire Genomic Resonance Gauge, a veritable means of measuring the power of a person's Void, Shu is vehemently opposed to Yahiro's ranking system. If implemented, it would suggest a survival prioritization of those bearing stronger Voids over those bearing weaker Voids. Shu is opposed to the ethical implications and the discrimination that might arise among the students if such a system was made public. A major, personal reason for this is the fact that Souta, who has become a close friend to him, is a Rank F - the lowest rank possible.
Upon discovering his rank, Souta bands together and, along with others classified as Rank F, Souta attempts to storm a hospital that is supposed to hold supplies in a desparate try to prove himself. Shu chases after them, but the students all get caught in an attack. In the ensuing chaos, Shu sacrifices himself to save Hare. Upon seeing Shu near death, Hare uses her Void to heal him back to full health. As she finishes this process, a stray bullet rips through her Void, killing her. Shu wakes just in time to see her dead body crystallize and crumble.
Hare's death was a major, emotional blow, and changed him dramatically. Misinformed by Yahiro over the details surrounding her death, Shu became a callous and emotionless person, implementing Yahiro's ranking system and taking control of the student body. Shu publicly assumes a tyrant-like persona with an iron fist, under the belief that extreme discipline will lead them to safety. However, in private conversations with Inori and Ayase, he realises his own actions are wrong and wonders if he'll ever be punished for them. During this time, he becomes extremely reliant on his Void powers, refering to himself as a King. Subsequently, Shu enters a state of shock when the ressurected Gai arrives and steals his powers by severing his arm.
After the loss of his right arm and Void powers, Shu enters a catatonic-like, unresponsive state, dwelling on his own mistakes, as well as dealing with the betrayal of people he believed to be his friends. During this time, in a reversal of roles, Inori takes guardianship of him, protecting him from the ongoing governmental hunt for Inori. Inori eventually decides to let herself be captured so that Shu can remain safe, as they no longer see Shu as a threat. After Inori's capture, Shu comes to terms with his mistakes and resolves to becoming a more decisive person.
Taking Arisa hostage at gunpoint, he demands she lead him to Inori. On the way there, he learns the hide-out Haruka, members of Funeral Parlor and his friends from school are using, and rushes over there. There, Haruka has another Void Genome ampoule, which she knows would kill Shu if he used it again. Aware of this, and how the Void Genome does not always respond positively to all its recipients, Ayase has decided to take the Void Genome on herself. Segai arrives, and begins an assault to retrieve the Void Genome and use it on himself. Shu arrives as Ayase and Segai are scuffling over the ampoule. Even when Haruka tells him that it will kill him, and Ayase begs him not to use it, Shu determines to use his power correctly this time, and injects himself with the Void Genome. His Void powers returned, he draws out his own Void, breaking free from his previous atittude of running away and hiding his true emotions from everyone. At his mercy, Segai asks if Shu can kill him in cold blood, to which he responds that he is willing to soil his hands to save his friends, proved when he stabs him with Yahiro's Void and severs Segai's life-line, killing him.
PlotShu is seen watching a video of Inori singing before going to school with Hare the next day. She asks him about what he was doing last night, since he looked tired but he just shakes it off. She tells him that there was a terrorist attack yesterday in Ward 24, explaining why so much of the GHQ were out guarding the area. Shu doesn't respond and just looks up at GHQ's base. After meeting with some of his classmates, Shu decides to eat his lunch at the back of his school in an abandoned building, only to find Inori, who he instantly recognizes, and Fyu-neru, who mistakes him for an enemy. However, after the whole misunderstanding is over, Shu tries to talk with her, while she tries to play cat's cradle with him instead. At this moment, members of the GHQ come to take Inori away and before Shu can defend her, they threaten with charging him as her accomplice, causing Shu to duck in fear. After they take Inori away, Shu starts to blame himself for what happened but is stopped by Fyu-neru who shows him a map to where Gai is. They reach the location, only to be ganged up on by a bunch of thugs. One of them hits Shu in the face before Gai shows up and scares them away with an impressive show of martial arts. Afterwards, Tsugumi comes and takes Fyu-neru away and Gai asks Shu if he just abandoned Inori. They are interupted by an explosion and it is announced that GHQ is attacking. Soon after, Shu is thrown back by an explosion caused by Ayase and she yells at him to get out of her way. Gai shouts at Shu to protect the 'key' (revealed to be the Void Genome) and he runs away to find Inori, which he eventually does. Shu, in a moment of strength, rushes to save her, resulting in the Void Genome's capsule being destroyed, precepitating Shu's new power, the "Power of Kings". After a brief flash of visions involving Inori, himself, fires and other currently unknown characters, Shu's power awakens, and he pulls a large sword out of Inori, sending a bright light, to the shock of all watching. Shu is fired upon by various missiles, all of which he diverts with the sword. He then destroys one of the GHQ's mecha with the sword and walks out of the explosion. As he's walking away, he's attacked by another GHQ member who fires missiles at him which he dodges by accidently activating a new power that let's him stand on platforms that send him into the air. However, the missiles follow him and he is sent crashing into the ground. He gets up and is saved by Oogumo, who crushes the GHQ member's mecha using a special device. Shu then runs to Inori to see if she was okay and notices that Inori's Void goes back inside of her and is confused about what it was. He then recieves a message from Gai through Fyu-neru to get Inori out of there in fifteen seconds. He later meets with Gai. They are interupted by an awakened Inori who asks Gai if she completed the job. Gai retorts that he was very disappointed in her. Shu interjects by saying he was being mean and that she worked really hard. Gai with the view that results were everything - therefore, she failed, since the Void Genome Shu had used was meant for Gai's own use. Gai explains that it was one of only three Void Genomes that Sephirah Genenomics managed to create. It bestows "The Kings Power" onto its user. Gai explains "The Power of Kings" is using Inori's Void as an example, stating that Shu is no longer allowed to powerlessly stand at the sidelines anymore. Before Shu can protest, Gai tells him that he can either sit quietly and be selected out of this world or he can adapt and change. Later, it is revealed that hostages were taken by the Anti Bodies (aka 'whitecoats') so Gai meets up with the rest of Undertaker and reveals his plan to the group as Shu and Inori stand by watching. Shu goes along with the plan and passes through a vent with Inori to arrive at their planned location, witnessing the extensive and cruel abuse of the Anti Bodies (such as Daryl repeatedly kicking a woman in the face) on the way. Funeral Parlor begins their attack, and Shu starts to fear letting everyone down. Inori encourages him, and says that she belongs to him now before he activates his power. As Guin counts down
At the end of episode 22, Shu is able to kill Gai and stop Mana with the help of Inori's Coid and soul. Inori regains control of her body but starts to crystalize and is blind. Shu embraces her in her arms and with the Void Genome on his hands (regaining Gai's Void Genome after his death) he uses it powers with his own Void to gather eveeryone's Voids and stop the virus for good. His body began to crystal until he envisions Inori holding a Cat's Cradle which he gratefully accepts. Inori disappears and her crystal body breaks down saving Shu.A few years have passed and Shu visits his friends in a birthday party of the deceased Hare. It is reveal that Shu's Void is gone, replaced with a metal postheic and has absorb Inori's blindness (holding a cane). Afterward, he listens to Inori's song while daydream himself in Inori's arms.
At the start of the series Shu's only noteworthy ability are his observational skills and intelligence of which he even received a slight praise by Gai. Since joining the Funeral Parlor, he tried to learn hand-to-hand combat and weapons use by Ayase and other members, but has never shown any skill at this, relying more on his use of Voids.
Shu's main ability stems from the Void Genome, refered to by many as the "Power of the Kings". With this power Shu can draw out a person's Void: an object that is refered as a person's heart and ideas taken form. This ability is highly versatile, as each Void is unique to each person and have several different effects that can be used to deal with almost any situation. In order to use this power, Shu must look directly into the person's eyes as he draws out the Void which causes the person to lose consciousness. Later he showed the ability to combine Voids to create more powerful weapons as shown by combining Inori's and Kido's Voids though it's unknown if he can do this with any Void.
One characteristic of the Void Genome is that when a Void is drawn, Shu can also generate blue-energy disks that can be used as shields or as stepping stones to reach higher grounds. This ability seems available whenever he draws any Void.
His most powerful and used Void is Inori's, a large and powerful sword that he can wield effortlessly and can easily cut through a group of Endlaves. He can also this to fire a thin metallic-like energy wave from the sword that can cut through most solid objects. Using this Void also appears to enhance Shu's physical abilities greatly, allowing him to jump and move at great speeds.
After Mana's destruction, Shu's powers underwent a change, as individuals no longer collapse from having their Voids drawn out, and can even wield them like Shu.
The Genome itself is apparently bound to the user's right hand, as this is the hand where the mark of the kings is and the hand Shu uses to draw out the Voids. In episode 17, Gai severs Shu's right arm and steals the Genome, which binds itself to Gai's right arm.
In episode 19, Shu regains his Void powers with another Void Genome ampoule - this time, it is situated in his left hand. He then draws out his own Void, which manifests into a crystalized right arm with green veins coursing through it, replacing Shu's missing right arm. With it, he can draw out and assimilate other Voids, allowing him to manifest and switch between several Voids as well as using them to their full potential. When this happens, the Void becomes black with a green lining in a similar fashion to his own Void.
This Void caries an extreme drawback - while it does take Voids in, it also takes harmful effects. Most notably, it takes the Apocalypse cancer from Souta, who was previously in a terminal stage of the Apocalypse Virus.