Back in the day, people were discouraged from using (traceable) real names on the internet. My first name is common and my last name is unique, so I didn't want to use either of them as a username.
The first discussion board I signed up with was a (now long gone) anime board. I wanted a name that was unique, but also ridiculous enough that no one else would want it. I can't recall all the different ones I tried but this was the one that didn't get any hits when I searched for it.
(Somehow, these days when you google it, you get a lot of hits that are not me. I guess it wasn't ridiculous enough. Today, the first hit that is me turned up on page 9!)
"Sakura" is both a Japanese cherry blossom and the first name of two of my favorite anime characters (from Cardcaptor Sakura and Sakura Wars.) When I was younger, I collected Giant Pandas -- stuffed animals, figurines, pictures, etc. These days I have a soft spot for Red Pandas too, but back then it was only the Giant Panda.
I prefer it with the hyphen in between, although I will use it as one word if wherever I am registering does not allow it. When the Japanese character "Sakura Panda" became popular, I considered switching my usernames over to "katiecb", but then I lost the consistency I had between communities. Now I'm sometimes "katiecb" and sometimes "sakura-panda", but mostly still sakura-panda.
