Submarine Released May 2021
AKATSUKI and RYUSEITAI meet in Okinawa during the SS Preliminary Rounds. After being sought out for help by the local idols, RYUSEITAI and AKATSUKI work on pushing back against ES. At the same time, Kanata comes into contact with local worshippers.
Worldbuilding for Ibuki
⦿ AKATSUKI and RYUSEITAI pushing out ES's attempts to dominate the local idols in Okinawa has direct results going into Supervillain and Stella Maris that are related to Ibuki and his grandfather.
⦿ This story introduces a side branch of the Shinkai religion. Kanata's interactions with them lead to the main plot of Stella Maris later on.
⦿ Based off of details about the remote island in the story, it feels like the concept of Hoshijima was kept in mind. The nondescript island is sealed off from the public and is an hour away from the main island by boat. Additionally, Keito tracks Souma down to the island via a GPS, not by a map (Hoshijima's existence was sealed off from the world. This included being erased from maps).
⦿ AKATSUKI and RYUSEITAI eat in a restaraunt together: Chiaki mentions that the owner is an old man who has strained his back. This detail matches a description given later on in Stella Maris.
Supervillain Released January 2023
Rumors spread of Tetora leaving RYUSEITAI to become the leader of a new group called RB (Ryuseitai Black). In an effort to pursue the truth, RYUSEITAI travel to Okinawa to find him. That's when they discover him situated in Crimson Production, an anti-ES agency based in Okinawa.
Worldbuilding for Ibuki
⦿ Tetora initially infiltrated Crimson Production under ES's orders, to have evidence of their wrongdoing. Tetora eventually discovers that the organization is actually a crime syndicate, that had previously held control over Okinawa before being dissolved by a group called Oni. Ibuki cooberates this in Idol Story 2.
Stella Maris Released January 2024
RYUSEITAI return to Okinawa to help revitalize land under the request of the lord of the island. Known as Hoshijima, it's a neighboring island inhabited by a community who have had contact with Kanata since the SS Preliminary Rounds. This story also heavily features two fine members, Tori and Eichi.
Worldbuilding for Ibuki
⦿ We learn about Hoshijima, an island made of meteorites that is under a curse. Long ago, a side branch of the Shinkai settled here. It was previously under the control of Priest, isolated from the world. Only after his death have they started to make contact again.
⦿ We meet a relative of Ibuki's - Mizusaba. Mizusaba talks about Ibuki and their grandfather (a pirate named Oni) at length throughout the story: Ibuki is the successor of Oni. Previously, Ibuki disappeared to America without a trace and couldn't be contacted.
⦿ Mizusaba tells us a little about Ibuki - He was a reliable figure in the community who helped whenever it was needed of him. He was unbeatable in fights. His western influence has influenced the main Okinawa island. Mizusaba also speculated that he may not be not suited for matters in religion.
⦿ In an Okinawan restaurant that Mizusaba works at, Mizusaba mentions that ever since their grandfather strained his back, they have taken on the role of transporting supplies to Hoshijima. This small detail connects back to what we learn in Submarine: That the owner of the restaurant is an old man with a strained back.
Ibuki Taki Idol Stories 1 and 2 Released April 2024
Our first introductions to Ibuki. Ibuki talks to Anzu in Idol Story 1, and ambushes Hiiro and Tetora in Idol Story 2.
Worldbuilding for Ibuki
⦿ In Idol Story 1, Ibuki mentions his grandfather - namely that after behaving badly, his grandfather "ripped off his horns".
⦿ In Idol Story 2, Ibuki comes to challenge Tetora to see the kind of person he is. It's revealed that it's because of Tetora's infiltration of Crimson Production.
VS★AUDIENCE Released August 2024
Thunderbolt Production is hosting a competition where idols compete to be produced by Nice Arneb Thunder, an accomplished, international producer and former idol. VS★AUDIENCE covers the third venue of these competitions, the Twin Rooster Pagoda, where idols compete in pairs to win the approval of hundreds of people.
Worldbuilding for Ibuki
⦿ This is Ibuki's debut event in the main story. In it, we learn Ibuki's motivations for coming back from America and joining 4piece.
⦿ Ibuki gets paired up with Keito for Twin Rooster Pagoda. Ibuki demonstrates having heard of AKATSUKI early on in the story, and confirms that it's "because he's from Okinawa" (though not canon or confirmed yet, this potentially indicates AKATSUKI had some impact during the events of Submarine).
⦿ In conversations with Hiiro, we learn that Ibuki has issues reading the room, so he acts aggressively to understand how people think. He takes a liking to Hiiro because of their similarities.
⦿ Nice-P initially scouted Ibuki for 4piece to be a solo idol. However, Ibuki's performance in VS★AUDIENCE gives Nice a new perspective of him.
Final Ceremony Released November 2024
When the results of 4piece are revealed, Ibuki leaves the ceremony and ponders his next steps. Keito seeks him out as soon as the ceremony is done to ask him a question.
Worldbuilding for Ibuki
⦿ Keito sees the moment as a golden opportunity and invites Ibuki to perform with AKATSUKI. Ibuki holds the same feelings and asks the same in return.
⦿ Esu explains that the original leader Nice-P had in mind for Special for Princess turned down the offer. Based off Nice-P's dialogue from VS★AUDIENCE, it may be likely that he intended to make Ibuki the leader after seeing "a new side of him".