Aoba Kuronuma

Aoba Kuronuma (黒沼 青葉 Kuronuma Aoba) is a character introduced in volume 4. He is a first year student in Raira Academy, and is Mikado's kouhai, who he refers to as "Mikado-senpai". He is the leader of Blue Squares. He has a bright personality and is always seen smiling, but has a darker side that is actually highly manipulative and cunning. He's described as being akin to "a younger version of Izaya Orihara". He does not appear in the anime.

Background
Aoba's parents are divorced. He changed his original surname, Izumii, to his mother's maiden name, Kuronuma.

Aoba has an older brother, Ran Izumii. When he was in elementary school, Aoba was occasionally abused by Ran who was jealous of Aoba because he received more attention. On one occurrence when Ran had overdid it, Aoba set his room on fire as revenge.

Blue Square
Aoba started Blue Squares when he was in middle school. He ceded its leadership to Ran, who, despite knowing Aoba was using him, accepted the offer as the one and only chance to surpass Aoba.

After Ran's capture, Aoba became the leader of Blue Squares again. He attempted to manipulate Mikado Ryūgamine for his own purposes, but Mikado quickly turned the tables when he stabbed Aoba's hand with a ballpoint pen when they were discussing an agreement. Aoba goes on to state that the deal was signed with the blood from his wound, realizing that Mikado had far from shown his true character.

At some point during middle school, Aoba walked downstairs to find Izaya Orihara sipping tea and chatting with his mother. Izaya apparently claimed to be Aoba's cram school tutor and had come to give his School ID back to him. Aoba knew that this was a blatant lie as he had his ID on him at that time but he didn't want to cause a commotion in his house. He and Izaya stepped out and discussed why Izaya had come. Izaya is suprised that Aoba was able to obtain his personal information through the Dollars network while Aoba is surprised that Izaya tracked him down so quickly. Aoba and Izaya immediately begin to dislike each other mostly due to the fact that their personalities are too similar. Aoba and Izaya also have another major difference. While Izaya loves humanity, Aoba hates humans with a passion. From then on, the two of them have been enemies ever since.

Light Novels
Volume 04: After the opening ceremony for the new year ends, Aoba approaches Mikado and Anri in the hallway. Aoba easily overwhelms the two of them with his cheerful personality (which vaguely reminds them of Masaomi) and asks if they can give him a tour of Ikebukuro since he doesn't know the area very well. Not really giving them the option to say no, the three of them set a date for the next day. Later on, during class, Aoba is placed inthe same room as Kururi Orihara. He sees Kururi's desk vandalized by several bullies. He realized that the only reason they were bullying Kururi was because Mairu was actually able to fight back while Kururi wasn't. Aoba simply ignored it until the teacher started asking who was responsible. Aoba ratted out the bullies without a second thought, much to their suprise. He didn't do it out of a sense of right and wrong but simply because someone asked him a question that he had the correct answer to. The bullies later confronted him about it and asked why he betrayed them. Aoba replied that he was never on their side to begin with and notices one of the girls bags on fire. After the bullies ran away, Mairu and Kururi show up and comment on how fast they can go. As Aoba realizes that it was probably Mairu who lit the bag on fire, he is kissed on the lips by Kururi as thanks for helping her. Before this information can register, Mairu also kisses him in order to get an indirect kiss from Kururi. As the twins leave, Mairu warns Aoba that, despite her appearance, Kururi is actually very aggressive. Aoba is left speechless.

The next day, when Aoba, Anri, and Mikado meet, they are immediately approached by several remnants of the yellow scarves looking for revenge. They are chased off by Kyohei and his group but the trio are also shoved into Togusa's van in the process. Aoba sees the Twins also in the back and is visibly surprised. After Toromaru catches up with them, the 9 occupants begin a frantic chase through the ikebukuro streets, eventually being joined by Celty. Eventually, Celty tells the others to run while she holds off Toromaru. Kyohei drops off Aoba and the others near a police station while he and Saburo went back to help Celty. Aoba and the twins head back to the overpass to out of curiosity and watch with confusion as Igor and Ruri dispatch Toromaru. Later, he attends the Hotpot party at Celty's apartment

Volume 05: Several weeks after the incident with Toromaru, Aoba invites Mikado and Anri on another tour through the streets of Ikebukuro since their last one was interrupted so suddenly. Mikado, having just recieved the warning from "Masaomi", tries to get out of it, saying he had errands to run. Aoba accepts it without any objections but also starts to (not so) subtley flirt with with Anri, even going so far as to switch from using "Sonohara-sempai" to "Anri-chan" without any warning. Although Anri doesn't initially pick up on it, Mikado panics and says that he actually will accompany them tomorrow and that his errand can wait. Aoba is visibly pleased.

The next day, as Mikado wonders what to do about the apparent attack on Toromaru by the dollars, Aoba comes knocking on his door. As Mikado wonders how Aoba found out where he lived, he also notices that Aoba wasn't the only one there. Several thuggish looking individuals were also standing behind Aoba. He asks Mikado to accompany them, saying that it's very important. Not having much choice, Mikado follows Aoba and his thugs to an abandoned warehouse where he finally asks why Aoba took him here. Aoba immediately asks Mikado if he's wondering about the Dollars attack on Toromaru. Mikado asks how Aoba knew that and Aoba plainly admits "We did it." while still smiling. As Mikado absorbs this information, Aoba also says that, while they are all members of the dollars, they also go by the name "Blue Square" It is revealed that the reason Aoba attacked Toromaru so violently was due to the fact that they interrupted his tour with Mikado and Anri several weeks ago and he was just venting his anger. He and Mikado recieve several messages from the dollars website about Toromaru attacking dollars members and Aoba says that it's finally started. Aoba then makes a strange offer to Mikado. He asks Mikado to become the next leader of the blue squares, intending to use him as a figure head like his brother Izumii Ran. He wishes to absorb the dollars into his gang and bring the Blue Squares back to their former glory. Aoba says that they'll do anything Mikado asks of them, even if it meant sacrifincing themselves to Toromaru. As Mikado denies this offer, saying that he could never order them around like that, Aoba steps closer to Mikado and claims that to be a lie, asking if Mikado knew he was smiling."

Volume 06: As Mikado tries to stall for time, Aoba is confused as to why Mikado hasn't made a decision yet. Despite his timid exterior, Aoba could sense the resolve Mikado could summon when the situation called for it such as with the incident with Yagiri pharmaceuticals or with the yellow scarves. Aoba soon comes to the conclusion that one of his long time enemies, Izaya Orihara must be involved somehow. He guessed that Izaya was trying to manipulate Mikado for his own reasons but Aoba refused to admit defeat. Aoba soon starts pressuring Mikado to make a decision by making subtle threats towards Anri. He says that if Mikado can't decide yet, Aoba can meet Anri while he stayed here to think about everything. Unbeknownst to Aoba, this action sparks a swirl of black emotions to form in Mikado's heart. The meeting is soon interrupted by the ringing of Celty's phone. With ther hiding spot exposed, Celty walks into the warehouse but tells them not to mind her and continue. As Aoba wonders what the headless rider would want with them, Toromaru also bursts into the seen. Aoba identifies Mikado as the leader of the Blue Squares, which cause Toromaru to turn their focus onto him. Celty and Mikado run while Aoba and the Blue Squares hold off Toromaru on behalf of their "Captain."

After the fight, most of the Toromaru members were either beaten or went after Mikado while everyone in Blue Square stood victorious. While stepping on another man's face, Aoba contemplates what to do next and sends one of his members, Gin, to take one of Toromaru's bikes and follow Mikado. Aoba soon notices another bike, Vorona's (which was supposed to be bait for Celty), and finds a thin black thread attached to it. Out of curiosity, Aoba and the Blue Squares follow it. As they go along, Aoba gets frequent updates from Gin who is watching the fight between Toromaru and the Dollars as well as the fight between Anri and Vorona. Aoba soon developes an interest in not just Mikado but in Celty and Anri as well. After Toromaru retreats and the fighting dies down, Mikado calls Aoba back to the warehouse to discuss their agreement. Mikado expresses his desire to fix the dollars and decides that teaming up with Aoba is the best way to do that. Aoba is amazed at how easily Mikado is falling into his hands and begins making plans for the future. Aoba juggles different plans in his head including how to get Izaya out of the picture, how to manipulate Celty into working for him as well as how to make his move on Anri.

Mikado soon proposes a written agreement to make their alliance official. Aoba is surprised but figures that he expected as much from Mikado. When he looks at the paper Mikado gives him, several alarms ring in Aoba's head. It comes too late as Mikado stabs Aoba's hand with a ballpoint pen. As pain erupts through Aoba's arm, he turns to ask Mikado what was going on. Aoba's words die in his mouth when he sees nothing but a cold, piercing glare from Mikado's eyes. Mikado states that his reason for this are for putting Anri in danger as well as attempting to take control of the dollars. Mikado orders Aoba to "stomach the full wrath of his anger."Before his men can react, Aoba tells them to back off. Aoba realizes that Mikado wouldn't back down-or let go of the pen- until he agreed. Aoba states that Mikado can use the blue squares however he wished and Mikado does a complete 180 in his personality. Mikado yanks out the pen and proceed to expertly treat and bandage the wound. Despite his docile and friendly personality, the fact that Aoba witnessed how flawlessly Mikado was able to switch between his two personas sends a chill down his spine. When Aoba leaves, he wonders in his head if Izaya had realized how they had underestimated Mikado and how he had far from shown his true nature. After all his planning, instead of the Dollars being absorbed Blue Square, it was Blue Square that ended up devoured by the Dollars.

Volume 08: Aoba becomes Mikado's second in command as he begins his "Cleansing" of the Dollars, however, Mikado still suspects that Aoba want to take control of the Dollars somehow. Most of the time, Mikado, Aoba, and the Blue Squares hunt down the "negative elements" in the Dollars (i.e. thugs who are simply using the dollars name as a scapegoat to increase their reputation) beating them up severely and banning them from the website. Aoba goes over to Celty and Shinra's apartment alone and attempts to make friends but they are cautios since Aoba gives off the same vibe as Izaya. When Celty leaves, Shinra threatens Aoba with a scalpel and warns him not to try anything that would put Celty in danger.

After the hunt for Adabashi Kisuke begins, Mikado and Aoba manage to corner him by Mikado posing as Ruri Hijiribe to lure Adabashi into a trap. While Aoba and the Blue Squares deal with his followers, Mikado opted to deal with Adabashi directly in order to take revenge for Shinra. After Mikado and Masaomi have a falling out, Aoba and the Blue Squares carry an injured Mikado to the hospital.

Aoba also joins the chatroom at the invitation of Mairu and Kururi under the handle "Pure Water 100%" along with several others. Also, unbeknownst to Aoba, his brother, Izumii Ran, was recently released from prison, has joined up with Izaya, and is out for revenge against him.

Volume 09: Aoba is seen hanging out with Mairu and Kururi at the Raira Academy pool. The three of them discuss what Izaya has gotten himself involved with as he has been out of contact for a while even in the chatroom (Izaya had switched to the alias "Chrome" without anyone knowing.) Aoba wonders in his head about how to get rid of Izaya but finds it hard to concentrate with the Twins in front of him. It's at this point that Aoba realizes that he has no idea how to act around girls at all. Eventually, the three of them part ways and Aoba gets a call from Gin. As they talk, Aoba realizes that Gin was talking on the cellphone while in the middle of another one of Mikado's missions. Gin is jealous that Aoba has two girls to hang out with and brings up the question of what Aoba would do if no one were close to him. Aoba ends the call and actually questions that possibility. Aoba shudders at the thought of being alone mostly due to the fact that he doesn't want to end up like Izaya who has isolated himself from even his own family. Aoba walks home, still wondering how to take Izaya down.

Trivia
His name "Aoba" translates to "Fresh Leafs", while his last name "Kuronuma" translate to "Black Swamp". "Izumii", his former last name before his parents divorced would translates into "Fountain".