How can I make 2d Sprites with 3d perspective in 3d environment?

when we heard about 2d we actually think its just a flat representation of an object with one side of it seen. But what I'm longing to learn is to create a 2d sprite with 3d perspectives. Its 2d but when the object turn around you can see its other perspective like Back Front Sides etc. uhm the best example is "Ragnarok Online." Mind you! I'm not trying to make a game as big like ragnarok online so dont think of it and get pissed saying negative comments. I just want to know If it is possible to make that kind of 2d aspects on a 3d environment in Unity. I was actually inloved with unity since then and I saw other game engines and programs which can actually do this things I'm asking. you might think why do I just use those programs so I can make it. but see here's the point If those programs can do those kind of things why Unity can't? seeing those programs is far behind unity. and I dont believe unity cant do it. maybe now I just dont know where to start and thats why I'm asking for help guys. hope you understand.

 

Try attaching a script that matches the camera's rotation on the Update(), something like:

gameObject.transform.rotation = Camera.main.transform.localRotation;

Similar thread here:
http://forum.unity3d.com/threads/9141-Billboard-perspective-stretching?p=270493#post270493

Or there are other (cleverer possibly faster) ways using the particle system:
http://www.41post.com/3770/programming/unity-creating-a-simple-billboard

 

can you give me more examples and source something close/ its quite confusing coz its statements are all about bill board no sample finished projects,