Kon

is an artificial soul modified by a Soul Society project known as "Spearhead" to inhabit a dead body and use his special powers to help the Shinigami fight Hollows, Kon's special power is in his leg muscles. His name is a short for. Ichigo uses him to transform into his Shinigami form, leaving him in charge of his body the way normal Shinigami use artificial souls to look after their gigais. When not serving this purpose, Kon usually inhabits a lion plushy.

Personality
Kon primarily serves as a comedic foil in the series; when not inhabiting Ichigo's body, his normal plushy body is treated with little respect and much disdain, sometimes bordering on abuse.

Kon is quite perverted and is preoccupied by sex much of the time. He will often try to take advantage of his plushy body to get girls to hug him to their chests. Kon is especially attracted to girls with large breasts, which makes Orihime the center of many of his fantasies. In the manga he is also seen using Ichigo's body to gratify himself while fantasizing about Orihime and Rukia.

Kon's redeeming quality, which allows Ichigo and Rukia to see him as someone worth saving, is his views on the sanctity of life. Because he spent many years in the form of a pill, fearful that one day he would be discovered and disposed of, Kon has developed a moral stance that prevents him from killing anything. He will also risk his own life in order to save even the lowliest of creatures, and is angered to see people who belittle their creations and dispose of them off-hand.

History
The Mod-souls were the product of a Soul Society project called "Spearhead". The goal of the said project was to modify artificial souls so that they could be inserted into dead human bodies and turn them into foot soldiers or cannon fodder in the war against the Hollows. Each Mod-soul had a unique superpower meant to help it fight.

Kon was one of the last Mod-souls ever created. Shortly after his creation the project was deemed inhumane by Soul Society and was shut down. All of the existing mod-souls were to be terminated. Kon, however, made a lucky escape, along with some other Mod-soul pills, and wound up in the storage room of the Urahara Shop, inside a Soul Candy dispenser. Urahara placed the tainted dispenser in a box designated as "poor merchandise" and had intended to dispose of it but for some reason never did.

Kon's plushy body was a fake version of Ponkichi, the main character of a popular TV show called "Carnivore Kingdom". It was purchased in the Karakura Town Festival for a child instead of a more expensive, official version. The child who got it didn't like the cheap knock off, and so threw it away.

Agent of the Shinigami arc
When Rukia realizes she won't have much more time in the living world before the Gotei 13 send someone after her, she decides to find a way for Ichigo to transform into a Shinigami without her help. For this reason she goes to the Urahara Shop and buys a dispenser of soul candy, which Ururu fetches from storage. Later, in school, Rukia drags Ichigo to a secluded corner and forces him to take one of the pills. Sure enough, Ichigo's soul is pushed out of his body and his body is now controlled by what seems to be an Artificial soul. Right then, Rukia's Hollow alarm goes off, and the two leave Ichigo's body in the hands of the supposed Artificial Soul, despite Ichigo's mistrust.

At about that time, Kisuke Urahara discovers that the dispenser he sold to Rukia was a faulty one, containing Mod-souls instead of soul candy, which Ururu delivered by mistake. He and his employees decide to set out and find it.

The Mod-soul, finding himself for the first time in a Human body, decides to hijack Ichigo's body for his pleasure and amusement. He wows a teacher by jumping over his head onto a rooftop 20 yards away. Next he surprises the girls in Ichigo's classroom by jumping up to the 3rd floor window from the ground. He makes a move on Orihime and kisses Tatsuki, throwing her into a fit of rage. Ichigo and Rukia return in time to find school desks flying through the window, they try to corner the Mod-soul but he jumps down from the window and runs away.

The Mod-soul goes off on a spree, leaping high and far through the air. His spree brings him near Ichigo's younger sisters' school, where he encounters three boys - Hashigami, Kaneda and Ino - who cut from gym class to play video games. He is enraged by the callas way the boys delete the game characters they created. He attacks the boys and breaks their game console. Later, as he makes his way away from the school, he senses a Hollow near the place he just left and doubles back, arriving just in time to drag the three boys out of harm's way. Rukia and Ichigo, in their search for the Hollow are surprised to find the Mod-soul, in Ichigo's body, taking a beating against it. Ichigo and the Mod-soul destroy the Hollow together, but the Hollow's falling body threatened to crush a trail of ants, so the Mod-soul kicks it away, putting himself and Ichigo's body at risk of falling off the roof. He later says that he refuses to kill anything or allow anything to be killed, because he feels anything has the right to live and die freely.

When Urahara arrives to retrieve his "poor merchandise", Ichigo and Rukia decide to keep the Mod-soul as the permanent means to replace Ichigo's soul, and agree to claim responsibility over the Mod-soul. They later find a lion plushy for the Mod-soul to reside in while not in use. Unexpectedly, the plushy comes to life, and Ichigo orders him to not reveal himself to the rest of the household. Ichigo chooses 'Kon', short for Kaizō Konpaku (instead of 'Kai', which sounded too cool) for the Mod-soul's name.

During the fight between Ichigo and Grand Fisher Rukia puts him into Ichigo's body to help her carry Ichigo's sisters. He later asks Rukia to go help Ichigo as a favor.

When he is fed up with the pains of living in the Kurosaki Clinic, he decides to run away but comes back after finding nowhere better.

When Uryū Ishida challenges Ichigo to a duel, Ichigo uses Kon to Transform. He later stops a Hollow from attacking Rukia and then confronts Uryū about creating the crisis for the sake of challenging Ichigo.

Before escaping the Kurosaki Clinic, Rukia tapes Kon to the bathroom to keep him from telling Ichigo of her escape, he later helps Ichigo decipher the coded note she left. Before leaving to help Rukia, Ichigo uses Kon to transform.

When Ichigo and his companions depart for Soul Society, Kon wishes to come along, but instead Ichigo leaves him in charge of his body and asks him to take care of his family.

Soul Society arc
Kon is recruited by Don Kanonji to the Karakura Superheroes and receives the name Karakura King. The team members use him as a crash test dummy for painful, seemingly useless and unnecessary experiments. Kon jumps from the frying pan into the fire though, when he decides to quit and gets himself abducted by a female Hollow who wants to keep him as a pet. The Hollow is finally vanquished by the team with Kon utilized as the weapon: Passed from Ururu like a volleyball to Jinta, hit by a Jinta Homerun towards Karin and finally kicked at the Hollow with the Karin Impact Kick.

Bount arc (anime only)
Note: Events occurring in this arc are only in the anime and do not constitute canon material.

At the beginning, Kon meets his fellow modified souls, Ririn, Kurōdo and Noba. He does not get along well with his new companions. Ririn views him as a fool and they often fight, and Kon is jealous of Kurōdo's assignment to guard Orihime. They do work together, however, most notably when they collaborate in the construction of several elaborate, yet useless, anti-doll traps.

When the Bounts infiltrate Soul Society, Kon joins Ichigo and the others to find them (partly due to fear of falling victim to Don Kanonji if he stayed behind in the real world again). Kon gets separated from the group in Rukongai and settles temporarily with a woman who owns a coffee shop. In contrast to Kon's usual lack of luck with women, this woman takes a shine to him. He eventually leaves to help fight the Bount, but continually arrives after the battles. After meeting up with everyone again (which is depicted during the non-sequitor previews for the next episodes), Kon brags about his stay with the woman, only to find out from Jūshirō Ukitake that it was actually a cross-dressing man.

Arrancar arc
With the Arrancar invasion beginning, Kon takes over Ichigo's body to have a little fun on the town, only to run into Grand Fisher. He is saved by the timely re-emergence of Isshin Kurosaki, Ichigo's father, as a Shinigami. Isshin quickly dispatches Grand Fisher with ease and Kon is forced to keep Isshin's true identity secret. Isshin reveals that he knew about Kon ever since meeting him during Grand Fisher's first attack at the graveyard.

Hueco Mundo arc
While Ichigo is off fighting in Hueco Mundo, Urahara makes Kon an offer to make him into a super hero to fight the Hollows in Karakura Town. Kon initially refuses, but jumps at the chance when Kisuke mentions he could become a 'babe magnet'. He becomes Konso Cop karakuraizer, and Urahara provides a background story for him: Kon, an evil space alien hiding among inhabitants of earth in order to carry out nefarious schemes, is captured by Dr. Urahara, a scientist on the side of justice, and turns him into the superhero karakura konso cop. Now, to return to his old alien self, he must lay to rest the 108 hollows that murdered Dr. Urahara's daughter!

He first destroys a large Hollow called Zonzain with his riserbeam. When other Hollow arrive so does the karakuraizer-team.Together with his team he destroys every hollow but then they spot a large fortress flying in the air.

After the destruction of the Hollows fortress, Kon soon falls asleep as Urahara's plans are completed for the final showdown in Karakura Town.

Beast Swords arc (anime only)
Note: Events occurring in this arc are only in the anime and do not constitute canon material.

Kon is seen in Ichigo's body sleeping during one of Ichigo's classes.

Powers & Abilities
Enhanced Strength: During the few times that Kon is in combat, he has proven to be able to hold his own — in addition to possessing all the combat abilities of Ichigo's well-trained body, he was designed to have exceptionally powerful leg strength. He was able to fend Ichigo off in combat by using just kick-attacks and leg-blocks, and is able to kick aside massive Hollows. He is also capable of jumping over 13 meters and 56 cm from standing position in Ichigo's body.

Enhanced Speed: Kon can run 100 meters in 3.8 seconds.

Spiritual Power: Being a modsoul, Kon possesses some spiritual power, though not as much as spiritually aware Humans, such as Yasutora Sado or Orihime Inoue.

Riser-beam: As Karakuraizer he can fire beam strong enough to kill a large Hollow. He first has to spell "Riser" with his body in charades, otherwise he will be electrocuted.

Relationships
Kon is treated as a necessary inconvenience by most of the people surrounding him, many of them acknowledge his existence by often unnecessary violence. The ones that do not are those who are non-violent by nature (Orihime) or by choice (Chad). Still, Kon has a more complex relationship system with several characters.

Ichigo Kurosaki
Kon is generally viewed by Ichigo as a pest. Ichigo often treats him in a less than gentle manner, which leads to Kon's initial choice to run away from the Kurosaki clinic, to which he eventually returns when he realizes no other place is safer for him. Kon has swiped Ichigo's body twice to frolic around Karakura, and got into Hollow trouble both times.

Rukia Kuchiki
Kon admires Rukia a great deal, and feels grateful to her for saving his life (when Urahara wanted to dispose of him). He refers to her as "nee-san", or older sister in the English version. Rukia seems to not return his affection, and will usually ignore him unless he offends her somehow, at which point she usually reacts violently.

Yuzu Kurosaki
Yuzu is one of Kon's greatest torments in living at the Kurosaki Clinic. She found him once while cleaning, and Kon was forced to pretend to be nothing more than a stuffed animal. Yuzu's given name for Kon is "Bostov"; she treats him as a female (despite the obvious mane on the plushy) and dresses him accordingly, which is insufferable for Kon. Despite this, when Yuzu cries herself to sleep during Ichigo's training period with the Vizard Kon shows compassion for her.

Uryū Ishida
Whenever Kon's cheaply made plushy body would get torn or scuffed, Uryū is the person to go to for fixing him. But Uryū, designer by heart, will sometimes make some unwanted changes to the plushy, such as dressing it like a designer doll. At this point Kon attacks Uryū, releasing all the anger he could never take out on Yuzu. Uryū removes the design, but at one point, he eventually sews a Quincy cross on the back of Kon's head for revenge. Oddly enough, he, along with other characters, appears to be completely unaware of the cross.

Trivia

 * His theme song, as chosen by Tite Kubo, is "Nichiyoubi Dansu" by Kuuki Koudan (Kon Theme #1) and "Bushman" by Rip Slyme (Kon Theme #2)

Quotes

 * (To Ichigo Kurosaki) "Right after I was born, Soul Society ordered the mod souls to be destroyed... and the day after I was born I was already chosen to die! Everyday while I was in that pill I was afraid. As I watched my friends disappear each day. Even after I got lucky and escaped the storage among other pills, I feared being discovered and killed. As I trembled in fear I would think... life isn't something that should be taken from others. I was born like this! I should at least have the right to live and die freely! Whether it's humans or insects... or even us... it's the same. That's why I won't... kill anything. 
 * (After Rukia Kuchiki stepped on him and he looked up her skirt) "Nice angle!"
 * (About Yuzu missing Ichigo) "How could you make this poor kid cry? What a worthless brother!"
 * (About Orihime) "Well, I could tell whether or not Orihime is the real one...if she would invite me into her Valley of the Gods!"
 * (Daydreaming about being smothered by women) "Extra large...puffy wuffy...booby woobies!"