Well, I can tell you that it's a later model Yanmar, built for the Japanese market, not the US Market. I don't know where you're from, maybe it was sold in your country if you're not from the US.
When you get a chance, click on MY HOME at the top of the page, then choose personal settings to fill out your profile. It will help folks to know where you are, and those who are close may be able to help more than we who are further from you.
The F455D is 45 HP at the PTO, about 50 HP engine. There are no English Language Manuals for it that I know of, unless you can find a translation at
www.hoyetractor.com
They are a fairly good source for information as well.
Also, you can post in the Yanmar forum on the Main Index page under Other Brands. There are a lot of knowledgable folks that go there, and many sell parts for these tractors.
I've only seen one F455D, and it was pretty awesome. You're going to find that parts are expensive, and sometimes difficult to get because there was no US equivalent to the F series when Yanmar was selling in the US.
I hope you'll enjoy TBN, and post some pictures of your tractor for us. I love the Yanmars, just didn't want the hassles that can sometimes accompany them.
John