Joshua is extremely intelligent, boasting a refined taste in addition to vast knowledge of both the RG and the UG. Unfortunately, these traits are often overshadowed by his air of arrogance. He thinks and acts on his own, always keeping his intentions mysterious, and is difficult to predict. He also tends to tease when he is not sharing information. Joshua rarely gets truly worked up about anything, usually faking it even when he appears to be exerting effort. These snobby qualities always make him appear condescending and antagonistic — especially to Neku. Nevertheless, his long history with Hanekoma has ignited a bond of trust between the two. Despite his interpersonal issues, he remains a mature and wise person at heart underneath his attitude.
Deep down, Joshua is simply lonely. Hanekoma reveals that Joshua had been alone most of his life without many friends. At the end of the game, Hanekoma notes Joshua's saddness while looking down at his friends (Neku, Shiki, Beat, and Rhyme) possibly because he is not able to attend the reunion. When Hanekoma asks about his feelings, Joshua remains silent and flees.
In Another DayEdit
"Another Day" Joshua's personality is much the same as "main" Joshua, unlike most characters, who have slight personality changes. He occasionally makes cryptic remarks, such as explaining that Shiki still appears in Eri's form because the player refuses to acknowledge Shiki's true form. It is implied that he has a similar position or powers to "main" Joshua, as evidenced by his remarks and knowledge. He is slightly more flamboyant than the "main" Joshua, but this may be simply acting to rile up his friends.
Both Joshuas meet in the Room of Reckoning. Unlike the rest of the group, neither Joshua is surprised by the other's existance.
In The World Ends With YouEdit
According to Sanae Hanekoma, before becoming directly involved in the UG, Joshua had the ability to see the UG while residing in the RG. Joshua would often visit Hanekoma to learn about the Reaper's Game. By the beginning of the events in The World Ends With You, Joshua is already the Composer of Shibuya's Reaper Game. Roughly a week before Neku is sent to the UG, Joshua begins a game with Megumi Kitaniji, his Conductor, to decide whether or not to erase Shibuya. Kitaniji is given thirty days to save Shibuya from its corruption and impotence, but his Entry Fee is not revealed explictly.
Later, while being chased through the RG by Sho Minamimoto, Joshua and Minamimoto end up in the Udagawa Back Streets, where Neku Sakuraba is admiring one of CAT's mural. Joshua shoots at Minamimoto, barely missing. Minamimoto retaliates with a repeated fire, but Joshua stops the bullets midair and drops them to the ground. After Minamimoto flees, Joshua shoots Neku, to use him as his proxy against Kitaniji as Neku has a great amount of Soul and a vivid Imagination. Joshua finally drops a Player pin on Neku which accounts for Neku's second player pin (in addition to the one he received for playing the Reaper's Game).
Joshua's rise to the position of Composer or previous history is not discussed. One possible hint is the description on the Eden pins, stating the equal judgement of the five kings, or the five different sets of pins of Gatito, and the goddess blessing her light upon a single individual.
Joshua spends most of this week hiding from Kitaniji. Neku runs past Joshua as he is fleeing the Noise on the first day. Joshua also observes Neku and Shiki throughout the first week after they form a Pact and battle the Noise at the Statue of Hachiko. Joshua keeps in touch with the Producer, Sanae Hanekoma, and constantly requests items from him, including improved phone functionality for the following week.
Joshua waits for Neku at the Statue of Hachiko and when he finds Neku looking for a partner he "helps himself." Joshua becomes Neku's partner for three reasons; to confirm Kitaniji's strategy, to teach Neku, and to protect him. Right from Day One, Joshua's attitude and behavior both irritates Neku and strikes him as highly suspicious. Joshua makes and receives calls on his phone, which had proved impossible for Neku and company in the last week. Joshua raises further suspicions when he reveals that he has been watching Neku, and that he is participating in the Game voluntarily. These irritations and grounds for distrust prove to be a psychological strain for Neku, who only manages to stay in the Game motivated by his Entry Fee.
Throughout the week, Neku scans Joshua with his Player pin and is led to believe that Joshua shot him from the images seen in his mind. This is even more suspicious because Players are not capable of scanning other Player Pin holder, implying that Joshua does not have a Player Pin. Meanwhile, Joshua regularly nags Neku to visit Hanekoma's coffee shop to receive items and upgrades for their phones. One upgrade allows them to detect Kitaniji's Imagination, and another upgrade provides the phone cameras with inter-temporal picture recording capabilities. Towards the end of the Week, an attack by Taboo Noise forces Joshua to reveal a greater portion of his powers.
On the final Day, Joshua and Neku go to Pork City to fight Minamimoto. The two gain the upper hand and defeat Minamimoto, therefore winning the Game. However, Minamimoto lets loose the level i flare. Joshua shields Neku from the nuke, pretending to sacrifice himself. At this point, Neku reads another thought from Joshua which implies Joshua never killed Neku. In actuality, Joshua had teleported away to another dimension: the dimension of Another Day.
During most of the week, Joshua is in an alternate dimension until the final day of the third Week. When he arrives at the Shibuya River, he finds that Neku had defeated Kitaniji and reveals his identity of Composer to Neku. He is integrated by Kitaniji along with Shiki and Beat, and Neku is forced to defeat Kitaniji once and for all. Having won the bet with Kitaniji, Joshua is free to destroy Shibuya, but instead wagers a game with Neku: both wielding a revolver, whoever shot each other first would decide the fate of Shibuya by becoming the Composer. Neku cannot bring himself to shoot Joshua, and so Joshua wins, but because Neku had changed and showed trust in Joshua, he decides to spare Shibuya, stating that if the worst person in Shibuya can change, then so can Shibuya itself.
In a secret epilogue unlocked after collecting all Secret Reports, Joshua in his true form is seen observing Neku and his friends meet up at the Statue of Hachiko with Hanekoma.
There are two versions of Joshua in Another Day: one from the main universe that teleported to this one after the battle with Minamimoto, and one born in that universe. Joshua plays Tin Pin Slammer for a while, and hides in his base in the Shibuya River as well. It is implied Hanekoma eventually finds him and brings him back to the Underground, most likely after letting Neku play a "game" with him: Final Time Attack.
In Kingdom HeartsEdit
Prior to the events of Kingdom Hearts 3D: Dream Drop Distance, Joshua saved Neku and the others from the brink of obliteration by bringing the remnants of their dreams to Traverse Town when it appeared before him and uses Rhyme's dream to open the portal into it. However, Joshua did not expect the dreams to assume physical form in that world, and he decides to help in their restoration after learning that they have been separated from each other in what he believed to be two Traverse Towns existing in the same space. But through Rhyme's memories, Joshua was able to exist in both versions at the same time.
When Joshua meets Riku in the Third District of Traverse Town, he tells him of the goings-on in town while offering his assistance. While Riku initially rejected his offer, he accepts once Joshua tells him that he knows Sora and that he is in the same world with them. The two are then confronted by Beat soon after, who challenges Joshua in the belief that he can return to his own world with Rhyme if he beats him. Joshua stands aside, watching with amusement as Riku fights and defeats Beat's Dream Eaters, and chuckles after Beat concedes the fight in frustration. Neither of them notice Riku passing out, and neither are there when he comes to. After Sora defeats the Hockomonkey in the Fifth District, Joshua appears before him and explains that he and Riku are in two separate versions of Traverse Town, as Sora sees an illusion of Riku and the unknown figure in the black coat. Riku sees a similar image of Joshua, Sora, and Rhyme after he defeats his side's version of the Hockomonkey.
Later, Joshua speaks to Sora and Riku simultaneously, revealing how he brought the others to Traverse Town and the world being splintered in two. He also tells them about how they are able to see each other is because of the strong bonds between, using Neku Sakuraba, Shiki, Beat, and Rhyme as examples. After answering Sora and Riku's shared question with an ambiguous answer, the version different if "he has close friends" in the Japanese version or "who he really is" in the English version, Joshua sprouted wings and flew off.
On Sora and Riku's return trips to Traverse Town, Joshua coordinates between them in order to help Neku and the others defeat the Spellican. He leads Riku into the Third District to trap Spellican in the Trasverse Town where Sora attempts to take it out. It was by that time, after Neku and Beat are reunited with their respective partners, that Joshua confided to Riku that his previous theory, of the two Traverse towns being parallel worlds was incorrect but more like the dreams of two different people. This leads Joshua to warn Riku to be on his guard as either version could be a trap.