Japanese culture. From visiting different places and the internet. Sometimes inspiration can come randomly but a lot of the time i get these idea's in my head suddenly because i think about anime so much even at work.
My clans, which are only 2 XD Both came pretty much out of my head, and slightly based on canon. For example the Urokome clan had a long history of experimenting on people, that was based on Orochimaru(Also had the idea of Orochimaru being a descendant of that clan). And are affiliated with the white snake sage because I'm just into anything with snakes x''DDD
Miho's clan, the Fushojiki's are pretty much random. Though they have a specialty jutsu that looks kind of like the Hozuki clan, their hands as pistols XD (Though I made that up before that signature move was even showed) However I have never really fleshed out their whole clan perfectly enough, sometimes I'm still unsure about it all OTL
Rest of my OCs are pretty random too, idek. since I just sit at home most of the time I guess I sometimes get inspired by looking at other OCs
ramble ramble after I finished I reread the poll, I first read 'how' instead of 'where'
For my Naruto oc's, it is just whatever pops into my head I guess. It usually happens if I had just watched, read, or drawn something Naruto related and BOOM another oc pops into my head. But of course it's not gonna be the final design ect for the character when it fist pops into my head. I end up changing them a bit more than they originally were but that is usually because of the inspiration that the show Naruto gives me. And of course if they seem a bit Mary Sue ish to me then I'll kick 'em down a notch of few. And so I guess it is a mix of ways to come up with my ocs.
I base my OC's storylines off of the canon storyline and then work off of that. I work at Laser Quest, so I'm in a maze for 15 minutes at a time supervising people while they play laser tag. Pretty much the entirety of my OC's stories and jutsus and clan information have all been thought of and figured out while walking around aimlessly for 15 minutes. But I do get help from my friends sometimes if I feel like something doesn't work well or if it seems to "sue"ish, ect.
I have a lot of clans and most of them are from a variety of things, myths or certain skills. Often I come up with a concept or a bloodline limit I want to do and expand from there. ;A; I get random inspiration from a variety of things and go off of that.
Most ideas for characters of mine are something I read ahead of time in a wiki or watched the anime for. Some characters are mine are inspirations of other characters from other anime as well.
Naomi one of my Naruto Shippuden OC is a crystal style user. I found this idea on the Naruto wiki and decided to use it before Shippuden even came out.
Hiroki another Naruto Shippuden OC is a wind style user. However, his jutsu comes from the palms of his hands that are covered in microscopic holes so nothing can block them. It's something I wanted to do from the typical wind style chakra user.
And Hikaru my Kuroko no Basket OC her home life as well as her playing are all inspired by Haruhi Fujioka from Ouran High School Host Club. But, her personality is somewhat like Misaki's on Maid Sama.
I think it's good to come up with ideas based on some studying of the anime or manga or having inspiration from other anime that are out there. ^^
Whatever hits me! Sometimes I just get some characters I decide are related somehow (they have similar appearances and abilities) so I kinda just work from there. I hardly ever start entirely from scratch. Other times I just get inspiration from studying something, like my one clan of geneticists came to me while I was studying genetics in an advanced biology class.