Summary
Koei Tecmo has spoken about how protective it is of itsDead or Aliveproperty, referring to the female characters as being “like daughters” to the studio. It’s an interesting descriptor, and Koei Tecmo’s standing on how copyright violations are handled withDead or Aliveis a bit unique.
TheDead or Alivefranchise got its start back in 1996 in arcades, with eventual ports arriving on Sega and Sony consoles in the years following. From the get-go, the series has featuredjiggle physics, which helped to set it apart from other games on the market. While the characters are meant to be sexy, the lengths to which fans repurpose the characters is something that actively concerns Koei Tecmo.

However, Koei Tecmo is also litigious when it’s deemed necessary, with Tomotoshi Nishimura, the general manager of Koei Tecmo’s legal department, stating that the company has shut down roughly two to three hundreddoujinshi(self-published fanart and comics), as well as two to three thousand pieces of online fanart every year.
Hearing the company refer to the highly sexualized characters ofDead or Aliveas “daughters” may strike some as a bit odd or uncomfortable. This is especially true when considering the origins of the series, with series creator Tomonobu Itagaki stating that violence and sexuality were both necessary to create true entertainment. However, the use of “daughters” may be due to a difference in languages. In any case, the developers don’t want to see their characters used in an overtly explicit fashion.
It’s also worth noting that Koei Tecmo doesn’t limit requesting art or projects to be taken down to sexually explicit works. The company also does this when fans' creations utilize characters from games that haven’t released yet, like the upcomingDead or Alivedating sim,Venus Vacation Prism: Dead or Alive Xtreme. While the wording is unusual, fans of the series can at least use Koei Tecmo’s stance as guidelines for what’s considered appropriate for fan works.