Here are a few options, depending on what feels most appropriate:
* サウル (Sauru): This is a straightforward romanization using katakana, the phonetic alphabet used for foreign words. It's simple and easily recognizable.
* シャウル (Shauru): Similar to the above, but using a slightly different pronunciation which might be preferred depending on the desired feel.
* A name with similar sounds or meaning: If you want a more natural-sounding Japanese name, you could choose a name that shares similar sounds or a similar meaning (if "Saul" has a particular meaning relevant to the context). This would require knowing the meaning and choosing an appropriate equivalent. This would be a more involved process and require additional information.
Therefore, サウル (Sauru) is probably the most common and easiest solution.