The platform is called PIGG.
PIGG is a japanese company Ameba's social network which is as a kind of virtual world like second life.
But something is different between pigg and second life.
Firstly, pigg is a web-based game which not requires you to install anything.
You can just open the web in the browser and you can start playing it.
Secondly, the style of visual is different.
Pigg is more cute and not really based on reality.(That may represent the Japanese culture of cute.)
My room and avatar :DFew reasons can explain why I am addicted to the game.
Firstly, I love the mini games in Pigg.
Pigg has many scene, for example Shibuya, New York and even space, my favorite scene is the casino. In the scene, you can really gamble(of course not using real money). I love to play black jack and slot machine there.
Not only gaining virtual money, pigg always offer events which will give presents (of course are for the avatar) to you when you win certain amount of money. The lovely and interesting present really attracts me a lot.
Casino yeah-------!Secondly, I love to chat with people in there.
Pigg has a funtion called "community". As the name said, it offers you a chance to join the community in the pigg world. You can really build friendship with Japanese with the function. I joined a community called 放送部 which are formed by people who enjoy watching live in a Japanese video website - niconico. It one hand can enhance my Japanese. On the other hand, it could let me have some new friends from Japan.
Finally, here is a video of demonstrating how to play pigg. Hope you enjoy it.

