I'm pretty sure I've written the whole story behind my name somewhere else, but I like typing SO, here we go again:
It all started about... 10 years ago? Something like that. I was basically watching this lovely anime Azumanga Daioh! with my sis and we both agreed that the character Kasuga Ayumu was some next level proper character. She had a propension to phase out, an absurdly quick wit (even if it didn't resonate with the rest of the world) and a buried killer instinct.
Look at that gorgeous bitch
Watch the anime or read the manga for further reference, since that image is basically the very first frame of her in the series.
When the day came to take a permanent nickname I decided to grab Osaka-san over those of characters of N64 videogames, basically because she had a personality, as opposed to the latter ones (the ones I played with at least). To this day I haven't found a personality I liked more on a character.
Later shortened to Osaka since I'm Spanish and need no honorary treatment.
PS: I go by "Riverside" on certain FPS games for obvious reasons, at least to those that have played KO or Smurfscup.