Japanese romanization is fairly standardized. Even if it weren't, creating in your mind a new alphabet for a new language using characters you already know isn'

Japanese romanization is fairly standardized. Even if it weren't, creating in your mind a new alphabet for a new language using characters you already know isn't that much work compared to learning a new alphabet, and it's a good place to start learning a new language. Just don't use the crutch for too long and you'll be fine.