Looking for a sauce i had today.

Greetings from the japan.

today i had a dish called Usuyaki at an restaurant in the japanese alps (matsumoto region). Its a pancake with nori, mushrooms and nozawana. It was served with 3 sauces: mayo, hoisin and the third one I didn't know.It was smokey sweet and had a taste slightly similar to oyster sauce.

Does anyone know what sauce this could have been?
Sadly I forgot to ask😅