Soy-butter is a flavor combination familiar to pretty much anyone living in Japan. Heck, even McDonald's gives out packs of Butter Soy Sauce for their fries.
I first tasted the combo at a New Years festival in Kyoto a couple years ago. There, the street vendors would grill the bright yellow corn over a glowing coal fire until deeply charred and nutty before dipping it into a bucket of soy sauce and butter. The concept was delicious, but the corn was sadly mealy and not particularly sweet. I vowed then and there that I'd make my own version when I got back to the States.*
*Japanese produce for the most part is remarkably fantastic (in flavor, appearance, and cost), but their corn tends to be lacking.
Using plain soy-butter is super simple and tastes great, but I prefer my slightly gussied up version which adds a hit of garlic and ginger to the butter and soy base along with some lemon juice (citrus and corn just go hand in hand in my mind). The whole thing gets topped with some finely sliced scallions.
It's not really Japanese, but damned if it ain't delicious.