It's odd. I lived in Fukushima for a couple of months when I first went to Japan, and my opinion of the Japanese rural landscape was far from favourable. 'No there there' was the feel. Flat and undistinguished, lacking the drama a Canadian thinks landscape ought to have (even a city Canadian, even one for whom 'rural' means the Niagara peninsula, another flat boring bit of the earth devoid of visual interest.) Okano captures the dullness exactly when she has Seimei wander all over Hyogo-ken with his melons; Ima Ichiko does it with her fen country. *This* is your storied countryside, replete with unseen spirits and Shinto kami and even more chthonic beings of the earth? Hardly likely. No wonder Ima's stagnant marshes yield human monsters; what else would go there?
(Mind, I've had a horror of fenland since reading John Gordon's House on the Brink, which someone is bats enough to describe as 'Wonderful, zany characters and a young girl who loves her dog make up this funny, and often touching, story for young readers.' More rationally, someone else links him to MR James.) (Follow the links at the bottom of that last and you'll find unfinished or unpublished James stories. Which I *of course* have no intention of reading myself.)
But then-- but then-- there are the inland mountains. They're quite different from Canadian mountains, but a much more likely abode of the ineffable than our bald stone giants. In Japan, forest and mountain go hand in hand; Japanese shade is somehow greener and shadier than Canadian (a phenomenon I noticed even in Tokyo); the light is tricky and places are difficult of access, which is why yer average gaijin doesn't actually see many of these interior areas. I only got approximations of what they were like in the hills back of Kamakura or in eastern Kyoto. The real mountains (or the real hills, in Canuck parlance) appear to be like those squared.
The mountains are not only Ginko's territory, and mushi territory, they appear to be the archetypal Japanese landscape (if an outsider may judge from their frequent appearances in popular culture.) The furusato, the place of traditional farmhouses and akatonbo and mist rising from valleys and snow falling on cedar forests and the sun going down behind the high ridge of hills. I can see all these in pastel shades if I want to (probably thanks to Hasui) but Uroshibara draws them in dark inks and grey hatching, so that the landscape becomes *full* in a way that it rarely looked to my eye. The deep woods of the deep hills, with their narrow tracks and scattered dwellings, is where you'd expect to find Japanese mythagoes, or whatever the plural is.
Which may be why the Mushishi timeline is unplaceable. I always think of it as mid-Meiji, just because generic western clothes and traditional together say Meiji to me, and partly because The Ballad of Narayama, whose world seems terribly close to the Mushishi one, takes place in Meiji. But it's more likely a Japan of the heart, a place you know even if you can't locate it in any one where or when.
I could also talk about the difference between mushi and trad youkai. For no good reason the traditional bogles feel much more city-like to me. They aren't, of course; kappa and kitsune are as countryside as you can get. But the pictures I've seen always have the long-necked guys, or the flying head guys, or the one-eyed guys, dressed as Yoshiwara geisha or merchants with chignons and kiseru. Ima's youkai or Natsume Yujincho youkai seem to take their cues from the human world; mushi OTOH are far quieter and nature-based and essentially indifferent to the humans whose life-strength they occasionally feed on.