It was recently confirmed that contrary to popular belief, the Persona 4 Golden PC port was handled internally by Atlus Japan itself, which has since set up its own official Steam developer page.
Persona 4 Golden launched on Steam this weekend, becoming the first ever Persona game to be available on anything without a massive PlayStation stamp on it. It's turned out to be quite the launch, in that Persona 4 Golden has already dethroned Final Fantasy 15 by smashing the record for the most concurrently played JRPG on Steam - exclusing MMOs - in the digital storefront's history.
One player is quoted on ResetEra as having said, "FYI, since the credits for the PC port are now available: contrary to speculation that this was a Sega Europe project, it appears to have largely been developed in Japan."
"The director on the port was Daisuke Yajima from Atlus, who was a programmer on P3/P4/P5," the quote continues. "The art director was Sachie Tousuji, who did interface design for P4/P4G/P5. Most of the actual development work appears contracted out to preapp partners, which is a Japanese dev house. All the programmers on the port apparently worked on the PC port of a Hyperdimension Neptunia game a few years back too."
The credits are now up on YouTube, and you can watch them below. However, beware: the credits contain spoilers for what's widely regarded as the true ending, so if you're experiencing Persona 4 Golden for the first time, you're probably best off saving the video for later.
Lastly, Atlus Japan has its own official Steam developer page now. This, combined with the astronomical success the Persona 4 Golden PC port has enjoyed so far, seems to indicate that other widely beloved Persona games may get the Steam treatment in future. Here's hoping.