Most Aisian nibs run fine to extra fine. It is rare to find a broad nib Asain made pen. Even an Asian made medium tends to more like a Western fine. An extra fine/ fine nib will lay down a drier line. I am left handed I use mostly a fine nib. A medium nib will lay done a slightly wetter line and your letters will be thicker, a broad nib puts down the wettest line and produces bolder letters.
Lastly a flex nib will let you adjust the wetness of the line as you write pressing the nib down.
Path of life is crooked, Christ leads me. (Brad) B.T.O.C.