Developement

According to the game director Katsuro Hashino, while "ideas [had been] thrown around earlier", development on Persona 4 in Japan did not begin until after the release of Persona 3. The development team consisted of the team from Persona 3 and new hires which included fans of Persona 3. Atlus intended to improve both the gameplay and story elements of Persona 3 for the new game, to ensure it was not seen as a "retread" of its predecessor. Hashino said that "to accomplish that, we tried to give the players of Persona 4 a definite goal and a sense of purpose that would keep motivating them as they played through the game. The murder mystery plot was our way of doing that." The plot of Persona 4 was "greatly inspired", according to Hashino, by mystery novelists such as Sir Arthur Conan Doyle, Agatha Christie, and Seishi Yokomizo. Persona 4 was officially unveiled in the Japanese gaming magazine Famitsu in March 2008. An article in the issue detailed the game's murder mystery premise, rural setting, and new weather forecast system. The game's North American release date was announced at the 2008 Anime Expo in Los Angeles, California. Atlus would not make an add-on disc or epilogue for Persona 4, as had been done with the Persona 3 FES.

The design of Inaba is based on a town on the outskirts of Mount Fuji. Its rural design was a source of conflict between Persona 4's developers, as "each staff member had their own image of a rural town", according to director Katsura Hashino. The entire staff went "location hunting" to determine Inaba's design. Inaba does not represent a "a country town that has tourist attractions", but rather a non-notable, "'nowhere' place". Hashino described the town as being "for better or for worse...a run-of-the-mill town". Unlike other role-playing games, which may have large worlds for the player to explore, Persona 4 mostly takes place in Inaba. This reduced development costs, and enabled Atlus "to expand other portions of the game" in return. A central setting also allows players to "sympathize with the daily life that passes in the game." To prevent the setting from becoming stale, the development team established a set number of in-game events to be created to "keep the game exciting."

Despite living in the countryside, Persona 4 characters were designed to look and sound "normal" and like "modern high-schoolers", according to lead editor Nich Maragos. Initially, he wrote the game's cast as being "more rural than was really called for." "The characters aren't really hicks...They just happen to live in a place that's not a major metropolitan area." While interviewing members of Persona 4's development team, 1UP.com editor Andrew Fitch noted that the characters from the city—Yosuke and the protagonist—have "more stylish" hair than the other characters. Art director Shigenori Soejima used hair styles to differentiate between characters from the city versus the country. "With Yosuke in particular, I gave him accessories, such as headphones and a bicycle, to make it more obvious that he was from the city."

During localization of the game, Teddie, known as Kuma in the Japanese games, was renamed for the western audience as the concept of a teddy bear was more familiar. Similarly, his verbal tic was translated from adding "kuma" to the end of his sentences to using "bear" in various words, such as a change from "very" to "beary". A similar change was done for Rise Kujikawa's stage name, "Risechie" (りせちー Risechī?) in Japan to "Risette" in the west, as it would not translate well for American and European audiences. "Risette" was chosen instead as French is considered cute in the west. This also changed a line she had in the game from "Rise-cheese" (りせチーズ Risechīzu?) to "Push Risette", the latter being a pun on the phrase "push reset". Nanba also explained the change from "Community" (コミュニティ Komyuniti?) to "Social Link", regarding the gameplay mechanic, as "community" has a different meaning in English, whereas Igor in his speeches often refers to "society" and "bonds". Dungeon items' names were also changed to English, such as the Kae Rail (カエレール Kaerēru?) becoming the "Goho-M", as the item's use of returning the player to the entrance was taken to be "go home". Other nuances include referring to a model robot in the protagonist's room, in Japan as the Mass Production Unit Brahman (量産型ブラフマン Ryōsanka Burafuman?) as the "MF-06S Brahman", making it a clearer reference to Gundam for the west, changing Junes's slogan from "Everyday Young Life! Junes!" (エヴリディ・ヤングライフ！ ジュネス！ Evuridei Yangu Raifu! Junesu!?, with "Junes" coming from the French Jeunesse for youth) to "Everyday's great at your Junes", and eliminating some Japanese cultural references that would not transfer such as the reference to Kosuke Kindaichi. There were also some issues regarding the translation of the names of Yukiko, Kanji, and Rise's dungeons, as the English names were made to fit the original Japanese graphics, and the "Void Quest" dungeon's graphics were specifically made to harken back to the NES. He also remarked on how popular the interpretations of Kanji's Shadow were in the west, and how it did not change how the character was seen by the other audience.

Atlus's senior project manager Masaru Nanba commented it was decided that "Shin Megami Tensei" was to be kept in the title of Persona 3 and Persona 4, as it was believed that they were part of the same series as Shin Megami Tensei: Nocturne; however the "Shin Megami Tensei" title was omitted from both Persona 4 Golden and Persona 4 Arena, as it would have been much too long. Similarly, Persona 4: The Ultimate in Mayonaka Arena and Persona 4: The Golden were shortened to the previously stated titles.