Unlike English, which is a stress language, Japanese is a pitch language, which means that it has low or high pitch on the morae of vowels, not stress. An English speaker typically mistakes Japanese high pitch for stress. In some cases, this results in the relatively undamaged representation of a Japanese word in English, e.g., the toponym Kyushu has high pitch on the first mora of the long vowel ō of the first syllable, and when this word is pronounced with initial stress in English, it sounds more or less authentic. But this doesn’t hold in cases like Tokyo, where both vowels are long and, moreover, high pitch falls on the first mora of the following word, hence, for instance, Tokyo desu ‘it’s Tokyo’ has high pitch on the first syllable of desu ‘is’.
What English speakers tend to do (besides mishearing high pitches as stresses) is to place a stress where it doesn’t correspond to a Japanese high pitch, as in Hiróshima/Hiroshíma. This toponym (like Tokyo) has a high pitch that falls on the first mora of the following word, all three preceding short vowels having low pitch, but the English rules of stress placement in quadrisyllabic words do not allow for ultimate stress in what looks like an English compound.
Occasionally, as in the case currently made notorious because of its damaged nuclear reactor, viz. Fukushima, English speakers happen to place a stress on the vowel corresponding to a vowel with high pitch in the Japanese original, which makes it (fortuitously) sound authentic to the ear of a Japanese speaker. Note even here, however, the alternate placement of stress on the element meaning ‘island’ (shima) following English prosody, which renders the original incorrectly.