Japanese can be written in English letters using a system called romanisation, which maps Japanese sounds onto the Latin alphabet.
There are several varieties of romanisation which produce slightly different versions of the same Japanese word due to differences in how they map to the sounds available in Japanese.
The most common system (particularly among English speakers) is Hepburn, but a different system called Kunrei-shiki is taught in schools and is often used to write Japanese names for passport. The English letters used for mapping Japanese sounds in the Hepburn system are a bit more intuitive than those used in Kunrei-shiki, so the romanisation of personal names may not always be what you expect.
松本 Matsumoto Matumoto
There are also several options for representing long vowel sounds, which can be dictated by style guides or convention rather than by the romanisation system in use.
大阪 Oosaka Oosaka? Ohsaka? Ōsaka?
The conventional English spelling ignores the long vowel and simply uses Osaka, which is also the case with Tokyo, where both “o” sounds are long vowels.
It’s not always feasible to ignore the long vowel though, as it can distinguish between two words.
おじさん ojisan ojisan (uncle, form of address for a adult man)
おじいさん ojiisan ojīsan/ojiisan (grandfather, form of address for an elderly man)