TV-Nihon

Spoiler

I was re-watching the episode and saw that in the background. Does it hold any significance, or is it just something that the waste company put there?

ちかよる (chikayoru) is to approach, or to draw near.

と (to) is a form of conjunction used in Japanese. It means "and".

キケン (kiken) means "danger", although I'm not sure why it is in katakana when it's not a foreign word.

To summarize, it probably means that danger is approaching.

Katakana is often used to emphasize words. It's like a cheap form of italics.

Also, here, it's not "Danger is approaching", it's "It's dangerous to get close". I'm assuming this is some sort of industrial area, and that does look like a pretty high wall, so it's just a sign warning people to stay away.

tl;dr Real world sign saying "keep out", nothing to do with the show.

Ah, thanks for clearing that up. I'm still learning Japanese now so my translations aren't always accurate.