A Twitter dispute highlights the lingering tensions between Sekai Project and the adult gaming community.
First of all, Dovac is the CEO of Sekai Project, a VN publisher focused on non-adult visual novels and indie games. Imouto Works is run by a single person who makes patches that add adult content to Steam releases of eroge. He makes these patches by combining files from the adult and non-adult versions; these patches don't work without the original Steam version as far as I know. His Steam restoration patch for Littlewitch Romanesque was endorsed by JAST, but Dovac regards Imouto Works as a warez site. I've contacted Imouto Works in the past to advise him on ethical practices, and he seems to be willing to listen to reason.
Sekai Project released KARAKARA on 6/28/16. This was a simultaneous ENG/JP digital release of both the adult and non-adult versions, and also a DLC patch that added the adult content to the Steam version. Sekai Project appears to have started offering these patches specifically to forestall Imouto Works, which had been "undercutting" Sekai Project by releasing "free" patches that add the content from the adult version of games like Nekopara Vol. 1 to the far less expensive Steam version. Sekai Project seems intent on charging hefty premiums for the privilege of accessing adult content, with the adult versions selling for as much as double the price of the non-adult versions sold on Steam.
Edit 7/31/16: In response to criticism here and elsewhere, Imouto Works has removed the KARAKARA patch from his site.
Edit 8/5/16: Dovac has deleted all tweets back to Nov 2015 and erased much of his Internet presence. Out of respect for his privacy, I will not try to reproduce the deleted tweets. Be aware that I used a degree of hyperbole in my descriptions of the links.