I know people are playing Phantasy Star Online 2 on the Japanese servers... I am not sure which 2.5D games you could play because games in North America get IP-blocked in Asia.
And many English games probably have Japanese language packs that you can manually put-in so that the players will speak English, you won't have the 0.2 second delay, and the text and voice-acting is in Japanese.
I was playing Dragon Nest with the Japanese voice pack:
http://forum2.nexon.net/archive/index.php/t-4478.html
But if you want the text in Japanese then try finding the Japanese version of a popular game from Japan - lol.