Are you looking for an operator's manual, or something else? If you bought your tractor from a dealer, they should have provided you with those things. If you got it in a private party sale, you may have a tough time finding literature. There are many companies offering parts, complete tractors, and implements for the imported brands; I haven't ever seen any advertising manuals for Iseki or Shibaura machines. That doesn't mean they don't exist, naturally.
If you just need some help with setup and features, posting specific questions may yield feedback from someone who has the same machine, or at least one similar enough that you can use their help to figure out yours. Welcome to tractorbynet!