Kobolds are originally just the “small folk” of German mythology with all of them being gnome-like but with varying degrees of hospitality. That’s why you get your mine Kobolds, your Heinzelmännchen and your Klabautermann.
Bonus fact: Dog like Kobolds in DnD derived media are not exclusive to Japan, in the Everquest lore they are also dog like (and a bit hyena like, whereas gnolls here are fully canine)