Creator's Favorite: Tomonobu Itagaki has gone on record to say, several times, Kasumi is his daughter, while showing no personal or close concern from any other character he has created or directed during his days at Team Ninja / Koei-Tecmo. The man was very protective of Kasumi too, openly admitting she would never appear in Ninja Gaiden, claiming Kasumi was too pure (despite being canonically the one to kill Raidou) and wasnt the type to engage in the same bloody works as Ryu Haybusa, allowing her less morally inclined sister, and almost as popular, Ayane to appear instead. Long after Itagaki had left Team Ninja, Kasumi started making cameos in Ninja Gaiden, becoming fully playable in Ninja Gaiden III, soaking herself in blood as much as Ryu and Ayane.
Franchise Killer: Dead or Alive 5 "milking" note Capcom Sequel Stagnation + DLC festival made the main franchise enter in a "Permanent Hiatus", essentially killing it for at least for the rest of the 8th Generation. And the fact the Team Ninja made an official announcement about it (which is very unusual) only reinforced that. Subverted when Dead or Alive 6 was announced at E3 2018, set to release in early 2019.
No Dub for You: While the fifth game as a whole is dubbed, the fighting game-related Guest Fighters (Akira, Sarah, Pai, Jacky and Mai) are stuck speaking one language regardless of settings; while Mai has new voicework done by Ami Koshimizu, the Virtua Fighter characters re-use voice clips from Final Showdown and it shows - they're noticably of a different audio quality when compared to the rest of the cast.
Nintendo decided not to release Dimensions in three Nordic countries Sweden, Norway and Denmark, due to concerns about some of its content raised by a small-town blogger. To paraphrase Upton Sinclair, said blogger aimed at Nintendo's heart, and by accident he hit the company in the stomach.
Koei Tecmo themselves decided to not release Dead or Alive Xtreme 3 outside of Asia. According to them, to avoid controversy in a time when the representation of female characters in video games have become a bigger concern than ever before in Western countries. However, given the non-Japanese Asian version of the game is localized to English (Except for voice overs), and given both the PS4 and PSVita are region free, this can be easily worked around by importing it from stores like Play-Asia.
However due to new censorship rules enforced by Sony in Japan, it appears Dead or Alive Xtreme 3: Scarlet may suffer this fate. A shame, considering Ensemble Dark Horse Misaki from Venus Vacation makes her first console debut for the PlayStation 4. This is somewhat mitigated since Misaki will and the other unknown character will be DLC for Fortune. You'd just have to get a Chinese PSN card.
Kasumi was played by Sakura Tange in the first two games but was replaced by Houko Kuwashima since 3 after Tange retired from voice acting. It's notable however that Tange returned to voice acting and played the roles of Kasumi Alpha and Alpha-152 in Dimensions.
Tange does not reprise her role as Alpha-152 in 5, that role is now played by Houko Kuwashima. This makes her the only Japanese voice actor that does not reprise their role from Dimensions.
Mami Koyama was the original voice of Tina in the first game, before Yuko Nagashima took over beginning with the second, and has been playing her in very game since.
Team Ninja originally asked Bungie for permission to use the Master Chief, which proved impossible due to storyline restrictions. But the staff at Bungie were intrigued with the idea and wanted to try something similar. As a result, Bungie developed the concept of a Spartan not entirely connected to the Halo storyline who could conveniently and somewhat plausibly be fit into the Dead or Alive universe. This concept evolved into the character of Nicole.
An early data leak suggests that Leon was originally meant to be in DOA5 before being cut mid-development due to time constraints. He returns in Ultimate.