Although not officially announced, it has been confirmed that a new game in the Neptunia series is in development by Compile Heart with producer Naoko Mizuno and illustrator Tsunako.
Here's a piece of a Famitsu interview with Compile Heart president Naoto Tominaga and director Hikaru Yasui (translated via Google Translate):
--The five titles we heard about this time are all scheduled to be released at once from spring to late summer of 2024. By the way, it seems that many of these five titles are made in collaboration with external development companies, but do you also produce other titles on your in-house production line?
Yasui: Yes. I am working on the numbering title for "Neptunia.'' However, since this is Compile Heart's flagship title, we are taking the time to create it carefully.
--How is the production of the new Neptunia numbering going?
Yasui: About two years ago, a small group of key staff, including producer Mizuno and Tsunako, began considering the content of the game, and they finally came to a point, or rather, decided on a direction. By the way.
--So, it seems like things are about to start in earnest.
Yasui: That's right. We have recently finished releasing "Neptunia: Sisters vs Sisters" (released in 2022) and its follow-up "Neptunia Game Maker R:Evolution" (released in 2023), so we are finally preparing to move on to new numbering development. We are at the stage where we are preparing.
――The new numbering is a bit disappointing, isn't it?
Tominaga: After the previous numbering was released, it was released on a new hardware such as PlayStation 5, and in that situation, suddenly creating a new numbering on multiple platforms would be difficult. So I decided to make it by sandwiching the two titles mentioned earlier. I think we will actually be able to deliver it after the release of the 5 new titles.
--got it. Finally, could you give a message to your fans?
Yasui : I'll do my best to deliver to you all the new works that are typical of Compile Heart, which I introduced a lot this time. In addition, we are also preparing titles that incorporate new changes and numbered titles of "Neptunia'', so please look forward to it.
Tominaga: "Is this kind of content coming from Compile Heart?'' or "Is this even going to be made into a game?'' We will continue to take on such challenges, so please look forward to it.
Is it going to be another mainline game? We'll have to wait and see when the announcement is officially made.
Source: https://www.famitsu.com/news/202310/05319425.html