okay, and what if the terrain is a plain field, nothing special about it? What then?
This is where you really need to be creative in what you do.
An easy way to do this would be to state somewhere in the match that maybe you keep your shuriken pouch on the opposite side than your opponent does.
This way if you reach to your right to grab a shuriken, but your opponents pouch is on their left, than when you grab your shuriken they'll have a fist full of nothing. And you can freely throw the shuriken at them without having to worry about them doing the same to you.
Or, for me, I keep a hand claw on my left hand. Something that not many people have, that way I can walk up to the opponent once they're trapped and punch them in the face or wherever. I'll get hit too, but I'll only be bruised, or at most have a broken nose, while they'll be dead from the claw piercing their skull. (Just an example, don't steal my way, find your own xd)
Also note that once the Kage Mane jutsu is complete (you have the opponent trapped) you no longer have to keep the rat sign. You can move however you want to.