Lost in Translation: Manner of Speech

When I started to translate this series, I agonized for quite a while about first-person pronoun. Should I use some sort of differentiation to mark which one is using watashi (neutral way of saying I) and which one is using ore (rough, masculine way of saying I)? For example, maybe by using bold font, underline, or a symbol (I, I, or I*)? I almost went through with one of them, but then I realized that this was only a part of a bigger problem.