It is well known that there are three kinds of Tokushuhaku (the specific timing morae) in the Japanese language such as the moraic nasal, the non-nasal consonant, and the long vowel. Even though Japanese native speakers can perceive them perfectly, it is difficult for Japanese learners from abroad to perceive and acquire them. To make it more efficient for Japanese learners to acquire them, how Japanese native speakers perceive Tokushuhaku needs to be investigated. This study examines the perception of a mora or morae specifically in the long vowel. Previously it has been assumed that duration contrasts along are involved in perception of native Japanese speakers. However it is hypothesized that the accentual change plays an important role for the perception of morae. Based on the hypothesis perception tests with computer-edited sound, stimuli were given to native Japanese, Korean, and English speakers. The results of these tests suggest that native Japanese speakers count the number of morae not only by the duration of vowels, but also by the accentual change which indicates the boundary between morae. On the other hand, non-native speakers count the number of morae only by the duration of vowels.