Tbh it really doesn't matter. The Japanese way of romanticizing their alphabet (which is called nihonshiki romaji) doesn't distinguish between short, long O (ou), or double O (oo) sounds. In Hepburn romaji (which is what you're taught in English > Japanese classes for learning purposes) it is spelled Ookami, but in nihonshiki it's just Okami. Which leads to all sorts of puns about dogs and gods like a certain video game.