Well then, I think that puts Nobotta's first person pronoun choice into some perspective lol. He's using what's basically the equivalent of Yami Bakura's first person pronoun of choice, ore-sama. lol
Kinda neat how -don could be used for both plural pronouns AND as an honorific like -san in Kagoshima, so his pronoun can mean either "my esteemed self" in a fittingly pompous sort of way (considering Nobotta's general attitude in the manga) or as the equivalent of "we" (which could ALSO be interpreted as the royal we, now that I think about it, which would be equally pompous in this fella's case, but it reminds me more of how the King of All Cosmos would address himself if he spoke Kagoshima-ben lol).
Makes me wonder if at some point, Nobotta (and one of his descendants, Oita, in the epilogue one-shot) would've dropped the -don from "oidon" at some point in his life after doing some self-reflection. I can kinda see that happening after some character development, especially since I don't think Tochiro himself addresses himself as "oidon" at any point in his life.
In fact, Tochiro's more toned down more standard dialect (particularly in Endless Orbit SSX as far as I've noticed, as I can't 100% pinpoint what his dialect is supposed to be aside from something very much influenced by standard Japanese) kinda reflects the real life influence of current Kagoshima-ben which is being further and further influenced by the standard Tokyo dialect with some former Kagoshima-ben terms falling out of use by the younger generation.
Also explains why I struggle to parse some of what Adachi says in the live action adaptation of Ganso Daiyojohan Daimonogatari lol. Not familiar with Kyushu-ben as it was in 1980 and prior.