Plus, I think the Steam client still doesn't have official Japanese language support.
There's no "official" support for most languages on Steam, most of the translation is done by community for free.
And you can't imagine how messed up could some Japanese publisher been, let's talk about KOEI, while Dynasty Warriors 8 was released on Steam seems like progression, but my story begins with Dynasty Warriors 7 on Steam.
There's a community hub (
http://steamcommunity.com/app/211140) and update news (
http://store.steampowered.com/news/8801/) for Dynasty Warriors 7 on Steam, but the game itself is not exist, no store page can be accessed, and it wasn't even caused by region-lock, so what happened?
KOEI use Steam as a DRM tool for Dynasty Warriors 7, the game was released in 2012 but only retail version is available, if you want add DW7 for your steam library, you have to purchase this game from some retail store in Hong Kong, throw away those box and discs, input the cd-key on Steam, the most ridiculous thing is: you can't even start this game without Steam (unless you pirate it).
When Dynasty Warriors 8 finally released a digital version on Steam, it's limited to English dub and sub, one month after that, the Japanese version and Chinese version released separately, and AGAIN, there's ONLY RETAIL VERSION for them, AGAIN, you have to active the code on Steam, and you can't start the game without Steam.
Living in 2014, KOEI Japan and KOEI Taiwan still treat Steam as a DRM tool, not a digital store, this is typical Japanese publisher.