Yoshikage Kira/Personality and Relationships

Personality
"I really want to reveal Yoshikage Kira's true nature to that girl on the right. I'd like to reveal my deep desires to her. I really want to touch her thin neck with my hands...and choke her to death."

Kira is a serial killer, characterized as highly egocentric and psychopathic, with a few obsessive-compulsive tendencies. He is also a hand fetishist.

Kira longs for a peaceful life, safe from any worry, and does not wish for it to be interrupted. Whenever that peaceful life seems assured, Kira adopts a jolly and confident demeanor. Although he is highly intelligent and possesses many talents, this yearning shows in his dislike of coming in first, and he even made it a point to never rank better than 3rd in any competition so as not to stand out. Since his youth, Kira has been avoiding standing out, living a healthy life. He becomes bothered when someone disrupts his habits and goes to extreme lengths to get it back. As his father pointed out, this will to stay in the background was so bad that if bullied or denied his favorite toy, Kira would bite his nails until they bled, being the only way he's found to express his frustration.

However, beneath his façade of a simple, humble salaryman, Kira is very abnormal. The most abnormal characteristic of Kira are his frequent murderous impulses. Kira targets women, or, more specifically, women with beautiful hands. Kira possesses a hand fetish, which he discovered when he found himself aroused by the Mona Lisa's hands. However, his desire has never extended to the rest of the female person. This results in murdering random women, not caring in the least how they look like or behave, in order to acquire their (severed) hands as "girlfriends", acting as if the severed hands were actually sentient and conversing with them, even offering them various gifts; when one "girlfriend" begins to decay, he disposes of it and goes off in search of a replacement. Kira is an opportunistic killer, his modus operandi being spotting a potential victim, following her to her house, and murdering her when both are isolated. His Stand erasing any proof, these murders are actually reported as missing persons. Moreover, Kira has expressed various other similarly violent impulses such as the desire to choke his victims to death and has horribly scarred at least Reimi Sugimoto.

Apart from his murders, Kira is particularly violent when someone threatens his way of life or publicly humiliates him. Since Kira doesn't want to be noticed, he will try everything to solve his problems without facing anyone directly. However, if he doesn't have any other choice, he will instantly try to kill whoever discovers his true nature. Kira is quick to drop his polite demeanor, rudely insulting his foes or violently beating them before killing them. After Koichi's Echoes ACT 3 results in Kira making a fool of himself in public and attracting unwanted attention, Kira went on his way to torture and humiliate Koichi, putting his shoe into his mouth and slamming his face against the ground. Kira has a hard time controlling these impulses, as seen when Hayato Kawajiri threatened to blackmail him. Kira lost his calm attitude and murdered him despite knowing he couldn't afford such a mistake.

Kira is also afflicted with a number of other quirks. Apart from his wish for a monotonous and tranquil life, Kira's OCD also makes him very meticulous and thorough. Kira has sophisticated tastes, notably buying his lunch at the best store in town as well as wearing Valentino suits. He doesn't tolerate any imperfection, and is even willing to lose time fixing Koichi's socks, becoming agitated when he sees them being worn inside-out. Furthermore, during his time as Kosaku Kawajiri, Kira made sure to perfectly mimic his new identity in every way, notably Kosaku's hand-writing, which he trained himself to do conscientiously. Kira's solitary nature is partially stemmed from his disgust of people who don't behave as properly as he does.

Kira is also an egocentric and selfish man, akin to a spoiled child. He doesn't care that is crimes involve murder and make his victim's relatives suffer. He only seeks to satisfy his basic instincts. In addition, Kira is determined to preserve his lifestyle, and being set back only increases his determination. Kira is also quick to shift the blame to someone else for his troubles, notably the Joestar group, for ruining his life. Kira possesses a twisted pride in having managed to mix his tranquil lifestyle and his serial murders for so long, and categorically refused to flee the town and live in fear, preferring to maintain a shaky façade of normal life with the Kawajiri's.

Kira believes that he has luck and fate on his side, exposing a superstitious façade, claiming that whenever faced with an obstacle he will be able to make it through with a combination of hard work and opportunity. He measures and collects his own fingernail clippings, using them to predict his murdering luck off of their length.

When Kira was pierced with the Arrow, his demeanor became much more relaxed and prone to elation due to his new-found power, which guaranteed that anyone approaching Hayato would be killed. Ecstatic to possess a power which would dispose of anyone who investigated him, Kira allowed himself one loud boast, which caused his downfall as Josuke overheard him claiming to be "Yoshikage Kira".

During his confrontation with the Stand Stray Cat, Kira expressed a desire to protect his "wife"  Shinobu Kawajiri and even showed relief at her safety; a feeling that confused him, and Kira rationalized it as him merely not wanting to arouse suspicion. Whether these feelings were genuine or not is left unanswered.

As a ghost, Kira lost all memory of his previous life and has thus lost his temptation to kill. However, his desire for a peaceful existence and his latent brutality remained.

Family
Yoshihiro Kira: His father is protective of his son, enough so that he was willing to support his son's murderous streak without a care. Yoshikage himself is shown to get along well with his father and trusts him to help aid in killing his allies and leading the peaceful life he desires.

Mother: It's not known how he feels about his mother, but it can be assumed he cared about her and got along with her as he does with his father.

Kosaku Family
Shinobu Kawajiri: In order to escape from Josuke and his friends Kira swapped faces with Kosaku Kawajiri and impersonated him, along with this having to also convince Kosaku's wife that he was really her husband, however Kira didn't know what sort of person Kosaku was in life, and unintentionally did things Shinobu knew Kosaku never did, such as cooking for her and even stealing money for the rent from the landlord himself. This caused Shinobu's feelings for her husband, or in this case Kira, to turn from loathing to actual romantic feelings. Kira on the other hand started to feel some sort of affection to Shinobu in return, as he actually saves her from being seriously hurt by Stray Cat, though Kira himself doesn't know why he had saved Shinobu and it is unknown if he actually cared about her or was simply faking affection before to keep her from suspecting him. It's unknown after Kira's death if she found out about him killing her husband and stealing his face.

Hayato Kawajiri: Hayato had a strained relationship with his father as well as his mother, and unlike Shinobu he notices the changes in his 'father' as he normally spies on both parents, and at first doesn't understand why his father would practice writing his name multiple times. It wouldn't be until much later when the relationship between Hayato and Kira would turn antagonistic when Hayato witnesses and films Kira murdering two people, and later on as Kira tries killing him he reveals he also filmed the attempted murder and uses that as blackmail. This causes Kira to panic over his secret being revealed yet again, and ultimately Hayato becomes the catalyst for Kira gaining the sub bomb Another One Bites the Dust, and is used by Kira as a trap for Bites the Dust to kill whoever asks about Kira, in this case being Josuke, Jotaro, Okuyasu and Koichi and forces him back to the beginning of the day whenever the sub bomb is activated. Hayato however eventually manages to use the time loop to his advantage and causes Kira to gloat about his victory right in front of Josuke, deactivating the effects of Bites the Dust and saving everyone.

Stray Cat: Kira saves Shinobu from Stray Cat but instead of killing it he keeps it up in the house attic, as he believes the Stand could become usual in the future. Following Kira being discovered by Josuke and the effects of Bites the Dust deactivating Stray Cat sides with Kira in the last battle, Kira placing Stay Cat in Killer Queen's hollow stomach and combining Stray Cat's ability to create air projectiles and Killer Queen's ability to create bombs out of anything it touches to create air borne bombs to use against Josuke and Okuyasu.

enemies
Josuke Higashikata: Having been informed about a murderer residing in Morioh Josuke joins in the search to find him, unaware that he, Okuyasu and Koichi actually first encounter Kira as he drives home. Things get serious though when Shigechi, another Stand user he and Okuyasu had befriended, had been killed by Kira after finding out he was Reimi Sugimoto's murderer. Josuke, along with everyone else increase their searching for Kira, the only clue from Shigechi being a button Harvest managed to steal from Kira's jacket. Getting an urgent call from Koichi at the Centipede shoe shop leads Josuke and Okuyasu right to Kira, after an intense fight with Koichi and Jotaro leave all three of them very injured. Having eavesdropped on Shigechi, Josuke and Okuyasu Kira knew about Crazy Diamond, and tried to trick Josuke into healing him, claiming he had been near the blast from the explosion caused by Sheer Heart Attack and pleads with Josuke to heal him. This however backfires as Josuke questions why Kira would even ask a highschool student of all people to 'heal' him, Kira having unintentionally revealed to Josuke that he could see Crazy Diamond, and revealing him to be the murderer they have been looking for, however Kira manages to escape and swap faces with Kosaku Kawajiri, and it wouldn't be until Kira's overconfidence would eventually give him away after loudly gloating to himself, with Josuke overhearing Kira, and because of this the effects of Bites the Dust were deactivated and once again Kira was found out, leading to one last fight between Kira and Josuke.

Rohan Kishibe: Rohan found out about Kira after encountering the ghost of Reimi Sugimoto, and would later find out that as a young boy Reimi was babysitting him on the night of her murder, and would have been killed as well if it hadn't been for Reimi pushing him out a window and saving his life. Along with the rest of the group he agrees to help find Reimi's killer, and eventually finds out Kira has now disguised himself as Kosaku Kawajiri after using Heaven's Door on Kosaku's son Hayato, however in doing this he is caught in the effects of Kira's new sub bomb Bites the Dust, and continues to die repeatedly until the effects are deactivated unintentionally by Kira himself.

Koichi: As with Rohan Koichi hears about Kira through the ghost of Reimi and joins in the search for her murderer, which only intensifies with Kira killing Shigechi. Later with Jotaro they use the button from Harvest and find Kira's jacket in the Centipede shoe shop, only for them to encounter Sheer Heart Attack. Koichi narrowly gets an injured Jotaro, who had taken most of Sheer Heart Attack's explosions, to the back shop where Sheer Heart Attack goes for him again, only for Echoes Act 3 to activate and use it's new powers to trap the sub bomb in place, causing Kira's left hand to slam onto the floor as well, causing Kira to get a few odd looks as he smashes a cup, table, rips off the clothes of a waiter and nearly get mugged as a result. Kira eventually gets to Koichi and stops the effects of Act 3 Freeze, and proceeds to brutally beat Koichi as a way for getting back at him for what Act 3 had done to him. Koichi, despite being injured and bleeding finds out Kira's name through his drivers license and taunts him that a kid had found out who he was, this drives Kira over the edge and he mortally wounds Koichi with Killer Queen, though Josuke later heals him with Crazy Diamond. Along with Rohan, Jotaro, Josuke and Okuyasu Koichi is caught in the time loop caused by Bites the Dust until the effects are deactivated.

Okuyasu: Okuyasu joins the group to help look for Reimi's murderer, and is shocked to learn Shigechi had been murdered by Kira, leaving the group to be on his own. Along with Josuke he would encounter Kira after his, Koichi's and Jotaro's fight and would later save Josuke from getting killed along with Aya Tsuji after chasing after Kira to her salon only to lose him. Along with Rohan, Jotaro, Josuke and Koichi Okuyasu was also caught in Bites the Dust's time loop and would later aid Josuke in his fight against Kira once the effects were canceled. During the fight Kira manages to seriously injure Okuyasu to the point where Crazy Diamond couldn't heal him, however Okuyasu survives Kira's attack and recovers from his injury.

Jotaro Kujo: The first time Jotaro would encounter Kira was in the Centipide shoe shop where Kira was getting a new button placed on his jacket after it had been stolen by Harvest in Shigechi's last moments, before he and Koichi could get a chance to see the name tag of the jacket they were attacked by Sheer Heart Attack, with Star Platinum's strength and Time Stop ability being unable to destroy it. Jotaro was the only one to figure out Sheer Heart Attack goes for the hottest thing in front of it and uses Time Stop again to create a fire, only to get seriously hurt by the resulting explosion and gets carried out of the shop by Koichi. Regaining consciousness after Koichi gets mortally injured Jotaro finally encounters Kira, who underestimates Jotaro by claiming nothing can beat Killer Queen, only to get caught off guard and surprised by the speed and strength of Star Platinum and gets pummeled before Jotaro lose consciousness once more. In the end Koichi and Jotaro deliver the finishing blows as Act 3 uses the freeze technique on Kira while Star Platinum beats Kira to the point of breaking his fingers, stopping him from using Bites the Dust on a nearby nurse before Kira accidentally gets run over by an ambulance.

Victims
Reimi Sugimoto: Reimi was the first victim of Yoshikage Kira and spends the next the rest of her life as a ghost, one day managing to warn Rohan and Koichi, and eventually the rest of the company about Kira still being active in Morioh. When fighting Shigechi Kira is taken aback and surprised to hear Reimi's name after Shigechi correctly confirms Kira to be her murderer, and once he dies he meets and recognizes her, and remembers a story his father used to tell him about never looking back in an alley when you die as Reimi tries to make him look at her back, and tries to force her to look behind her instead, but fails when Arnold bites his hand off and makes him turn around and get torn to pieces by a swarm of hands.

Arnold: Before killing Reimi Kira had slit Arnold's throat and killed him, possibly so he couldn't alert Reimi to any intruders in the house. Now a ghost after his battle with Josuke Kira tries forcing Reimi to look behind her so she'd get dragged away, however he saves Reimi by biting Kira's hand off, causing him to get torn to pieces by the swarm of ghost hands instead.

Shigekiyo Yangu: Kira had started following Shigechi back to his school so he could recover his sandwich bag that, unbeknownst to Shigechi as he believed it was his, contained the hand from one of his victims. He manages to get it back only for Shigechi to use Harvest to drop the bag and reveal Kira's secret. Kira, now having to protect his secret decides to kill Shigechi on the spot, and demonstrates Killer Queen's ability by using a yen coin as a bomb, causing immense damage to Shigechi. Caught of guard that Shigechi would even know Reimi Sugimoto's name he loses sight of Shigechi as he weakly tries to get to Josuke so Crazy Diamond could heal him, however Kira had gotten to the classroom door first, and informs Shigechi he had turned it into a bomb just as Shigechi had touched the handle, setting it off and killing him. Unknown to Kira at the time this would eventually lead to his downfall, as in his last moments Shigechi had used Harvest to steal one of the buttons off of Kira's jacket, leaving it as a clue for Josuke and company in order to find Kira.

Aya Tsuji: Kira and Aya didn't interact with each other before the events of Diamond is Unbreakable, however Kira did find out she was a Stand user, and after chopping his hand off to escape from Josuke and Okuyasu he makes his way to her salon, and forces her to use Cinderella to change his face with that of Kosaku Kawjira and mortally wounds her and turns her into a bomb and kills her when Josuke got too close to her.