GRUFF GUY is a character and NPC in OMORI. He is the father of KIM and VANCE and the ex-husband of the RED-GLASSES LADY. His signature characteristic is how often he grumbles and mumbles to himself. He's trying his best, but still messes up quite frequently. He cares for his kids, but doesn't know how to say "no" to them or be strict. He's a bit of a walking doormat who is trying to get his life together. [some description pulled from OMORI Wiki]

As his character description is "GRUFF GUY," you can assume... his voice needs to be gruff. Raspy and rumbly. Medium-low to low pitch. For whatever reason, I picture an old 80's rocker voice for him, too. (Maybe it's the mullet.)