Most “darkling beetles” (tenebrionids) are black, as the name suggests, but this species (kiiro-kuchi-mushi) is bright yellow. I found this specimen among some dead leaves next to a vending machine at night (near Inunaki Dam).

Cteniopinus hypocritaCteniopinus hypocritaCteniopinus hypocrita

Coleoptera: Tenebrionidae (darkling beetles)
Cteniopinus hypocrita = kiiro-kuchi-mushi