>>279992516
Here's Furinkan's note: "Foxes make the sound "kon" in Japanese (like a cow saying "moo" or a cat saying "meow"). Hence why the fox spirit adds "kon" after its words when it speaks. "Kon" also sounds like the sound of a cough, hence the joke of Tsubasa being sick will possessed by the spirit."

Yeah, VIZ changed it to "yip" since that's the closest thing we have to the sound a fox makes.