Yoshikage Kira

"I was just explaining what I do to go about my life quietly, with a calm heart. If you keep worrying about winning and losing, it'll just stick in your mind, and you'll be troubled. You won't be able to sleep at night if you're always worrying about your enemies. My attitude towards society as a whole has made me a very... content person. But if anyone stands in my way... I won't lose."

- Yoshikage Kira

Yoshikage Kira is the main antagonist of the fourth arc of JoJo's Bizarre Adventure, Diamond Is Unbreakable. He is a serial killer obsessed with women hands and who wants to live a quiet life with no repercussions for his killings. Yoshikage was voiced by Toshiyuki Morikawa in the 2016 anime adaptation and by Rikiya Koyama in the games JoJo's Bizarre Adventure: All-Star Battle and JoJo's Bizarre Adventure: Eyes of Heaven.

Story
When he was a kid, Kira was good at many things. But he always purposefully got 3rd place in competitions, because he never liked to call attention. When he grew, he started collecting his own nails. Every time his nails grew very fast, he sensed a uncontrollable desire to kill women. From this, he strongly wanted to not leave any evidence from his crimes, thus triggering the appearance of his Stand, Killer Queen. His Stand had the power of turning anything it touches into a bomb, even a human. With his new power, Kira felt very comfortable, because now he could live a normal life without raising suspicion.

For years he killed many women in Morioh Town, until one day he was carrying a hand from his last victim in a paper bag, which was accidentally exchanged by Shigekiyo 'Shigechi' Yangu, who was also a Stand user. In an attempt to recover the bag, Shigechi discovered him and engaged in battle with him. Kira smartly defeated him by turning a coin into a bomb. While trying to run away, Shigechi collected a button from Kira's coat. Kira killed him, leaving no trace of him, but Jotaro Kujo and Josuke Higashikata found the button that Shigechi had collected, and started investigating. When Jotaro, along with Koichi Hirose, found him, he left his Bomb N° 2, Sheer Heart Attack, to take care of them. His bomb was an automated vehicle with a skull face that could track heat and was virtually invulnerable. Kira managed to defeated them, but was badly hurt, when Josuke and his friend Okuyasu found him and unmasked him. On his attempt to run, Kira took a man hostage, and using Aya Tsuji's power exchanged his face with the man, leaving her with a bomb and with the man's identity.

After managing to escape, Kira assumed the identity of the man, Kosaku Kawajiri, and infiltrated his family in order to hide himself. But Hayato, son of the man he was impersonating, started suspecting of him, and decided to investigate by himself. He managed to film one of Kira's murders, which left Kira desperate. During his desperation, he was pierced by the magic arrow that was in possession of his father Yoshihiro Kira(who happened to be a ghost in a photo). This arrow had the power to turn anyone into a Stand user, but on Kira it gave him a new power. He set his new bomb, Bites the Dust, into Hayato, so anyone that questioned him about Kira would explode instantly, causing a time loop that would end only if Kira dismissed the bomb. Hayato managed to outsmart Kira with some luck by giving a phone call to Josuke, making him wake up early and arrive when Hayato is confronting Kira, who reveals his true identity without noticing Josuke's presence.

Unable to hide anymore, Kira dismisses the bomb on Hayato to confront Josuke and Okuyasu. Because Hayato had brought Stray Cat with him (in an attempt to attack Kira by himself), Kira takes the cat-plant and puts it on a hollow compartment in Killer Queen's stomach, being able to combine Stray Cat's air bullets with Killer Queen's bombs, thus creating invisible air bombs. He easily beats Okuyasu and sets a bomb on him, forcing Hayato to set the bomb off so Josuke could heal them both and continue the fight. Even though the air bullets were invisible, Kira was able to calculate their trajectory by using mathematical calculations, forcing Josuke to retreat inside a house nearby. They soon find out Yoshihiro had been hiding inside Josuke's pocket and giving instructions to his son, so Josuke gives Kira a fake instruction, which ends killing Yoshihiro. Josuke finally defeats Kira by using his restoration ability on glass shards stained with his blood, which home in to Kira, who had also been stained with Josuke's blood.

Finally exposed, Kira is unwilling to accept defeat and attempts to activate Bites the Dust again. He soon finds himself in an alleyway, believing he has won, but the ghost of Reimi Sujimoto, his first victim, confronts him and reveals he's having delusions, as his attempt at escaping had been foiled by Koichi and Jotaro, after which he was accidentally run over by an ambulance. Reimi reveals her back wound to Kira, who finally recognizes her but wonders why she would reveal herself to him like that. He then notices he's on the Ghost Alley, a place in which you cannot look back, or your soul is dragged into the underworld. Thinking that maybe this is the peace he longed for, he attempts to make Reimi look back, but her dog Arnold (which had also been killed by Kira) bites his hand. As he falls and turns around, various ghost hands grab him and drag his soul into the underworld.

Powers
Kira has varied powers at his disposal, all of which are related to bombs. First, his Stand, Killer Queen, can turn anything into a bomb (even people) by just touching it. Killer Queen may motion pressing an invisible button to detonate the last object it touched, leaving not a single trace (unless Kira wants it). His second power, the Bomb #2, is a miniature tank-like rover with a skull face and cat ears called Sheer Heart Attack deployed from Killer Queen's left hand that acts automatically, seeking any heat signature in the area and exploding on contact. This bomb is completely indestructible, and will explode as many times as needed, until Kira calls it back, with its only weakness being that whatever happens to it aside from direct damage affects Kira's left hand as a result. After being pierced by the Arrow, Kira gained a third power, called Bites the Dust. He can set this bomb in any non-Stand user who knows his secret. If this person is interrogated about Kira, this miniature version of Killer Queen will enter the interrogator's eye, proceeding to explode the person immediately, with the added effect of distorting the flow of time, resetting the day. Once the day is reset, regardless of the number of times, even if the person doesn't ask about Kira or is avoided for that purpose, they will still explode at the exact time as the first incarnation. Bites the Dust will also protect the person from anything, even from Kira. The flow of time will only return to normal if Kira dismisses the bomb.

Personality
Yoshikage Kira's defining personality trait is his fetish for the female hand. This stems from an erotic fascination with the hands of the Mona Lisa as a child. Any woman unfortunate enough to fall victim to him will lose their hands in death, which are collected as "girlfriends".

Kira is very calm and over-confident, rarely losing control of the situation. He demonstrates great cunning when handling obstacles and problems, a trait common in major characters of the JoJo series as a whole. He will kill anyone who gets in his way mercilessly, but compared to the other villains of the franchise, is among the more human antagonists. This is demonstrated when he, an office worker, is frequently asked out by female coworkers that all have the potential of being his victims as he denies them more often than not (not out of actual respect for their lives, but selectivity for their hands). Kira finds his ability to eliminate victims and witnesses without a single trace as a source of arrogance, as he believes this, combined with his strategical thinking and "luck", make him an unstoppable killer.

Kira's status as a serial killer is supported by his inherent desire to not want to draw attention. This trait has been apparent since his youth, combining both his skill and this factor to always score 3rd place in any competition without fail throughout his school years. A lifelong habit derived from this is the quiet biting of his nails to the point at which they start bleeding whenever he is under a lot of stress, not even wanting help from his parents in such a case, as they are not an exception to that wish. The result is his signature tagline, "Yoshikage Kira just wants a quiet life."