Continuing last week’s oni theme:
(Wataru seken ni oni wa nashi; “Across the world, there are no demons.”)
Nobody in the whole world is an oni – i.e. a purely malicious being. “There is kindness to be found everywhere” Alternately, not all people are evil. There is no need to distrust every single person you meet.
First is the verb 渡る (wataru; to cross; to span) – acting to modify the noun 世間 (seken; the earthly realm, human society). に (ni) is a particle indicating, in this case, location (e.g. “within”). Oni is as it was last week – a malevolent mythical monster (and grammatically, a noun). Wa is our topic particle. In this case one could argue that there is a contrastive nuance – in this world there are no oni, but in the Buddhist hells or other unearthly realms there are plenty of them – but I feel that the feeling is emphatic rather than simply contrastive. Finally, 無し (nashi) is an adjective of negation in sentence-final form.
In contrast to last week’s use of oni as an exemplar of physical strength, there are quite a few kotowaza that turn on the oni‘s reputation for being malevolent to humanity, even nasty for the sake of nastiness. The creatures are, of course, used as a metaphor for people whom you wouldn’t want to meet, but here we have an optimistic affirmation of basic human goodness.
無し can be rendered in a more modern way as 無い (nai) with no change in meaning, although the feel of the former is more deliberately archaic or formal.
A more dramatic version of the phrase goes 地獄にも鬼ばかりはいない (Jigoku ni mo oni bakari wa inai); “Even in hell it isn’t only demons.”
(“Hidoi me ni atte, zetsubou shisou deshita ga, Tamura-san ni iroiro tetsudatte itadaki, hontou ni wataru seken ni oni wa nashi da to omoimashita.”)
[“Some bad stuff had happened to me, and I was about to lose hope when Tamura-san helped me out with all sorts of things. And I thought, nobody is all bad after all.”]