In relation to what @keii4ii said above, but also addressing the whole topic . . .
My pen name was originally a gag between me and my childhood best friend, who also coincidentally shared the same last name as me (different "clans" though, if that makes any sense; my side is French and First Nations, while hers is French and Irish and Dutch and a whole other slew of stuff lol).
We played a lot of video games and watched a lot of anime, you know, the typical kid noobs, and when The World Ends with You was released, we were both hooked (she even bought it just so we could play multiplayer). There was a character we both loved in it, a Reaper named Uzuki Yashiro.
Cue the references that caught on xD
I took the nickname Uzuki, she took Yashiro. These names ended up sticking like glue, and I ended up using mine professionally by the time I was in senior year and had already done a lot of projects under it. She still calls me Uzuki, I still call her Yashiro, it's just never worn off. And of course, the concept of Reapers plays a role in Time Gate: Reaper, obviously lol
So just Uzuki with my last name attached to it. The real life Yashiro doesn't do this, she's just gone by Yashiro, and she just uses it as a standard username, not quite to the extent that I use it to. My real name is nothing unique or special or complicated (in fact it's one of the most white trash names ever, bonus points to anyone who knows it or can guess it from that assumption alone xD). As far as I'm concerned, Uzuki is my real name, despite my real name being the name that's on my birth certificate, ID, driver's license, school card, etc. I'd like to have it legally changed to Uzuki, or at least have it added to my middle name, when I have the money to do the paperwork, get all my ID's changed, etc (and that costs a lot of money lol). I as well as many others who know me as Uzuki use Uzuki; it's gotten to the point that even my boyfriend never uses my real name, and hasn't called me by my real name in months (I don't use his regularly either; just "Miko".) So it's at the point now where if I'm called by my real name by people who know me, like Miko, I feel like I'm about to be yelled at xD (like when people say your full name to yell at you).