Hi Masamune. I have 2 blogs. One at Blogger and one at Wordpress. There are other hosting services, but I haven't tried any others yet.
Blogger is the easiest to use, for me, but you will have to sign up at any service you use.
As far as anonymous blogging goes, I use a yahoo account I made just for that purpose and don't use any real names or anything, but really, in a near totaltarian age like we live in today, i dont think thereš anything you can do if someone really, really wants to identify you.
I could be wrong though, as there are a lot of brilliant computer savvy people out there, but Im not one of them. :)
_https://www.blogger.com/start
_http://wordpress.com/