Chinese L2 learners of Japanese are identified as showing difficulties in the production of Japanese geminates. The idea of being difficult-to-listen is embodied in the concept Comprehensibility (Derwing & Munro 2015). This study first reviews the native pronunciation of Japanese singleton vs. geminate contrast. Then, we report findings based on the pronunciation by 20 Chinese learners of Japanese and discuss the issue of comprehensibility in geminate production. While the contrast in the closure duration between singleton and geminate consonants shows a similar pattern to reported Japanese speech, the learners show large differences in the vowel duration preceding and following consonants. We report findings from a linear mixed model that was run with speaker as a random effect. The results show that participants do not make differences in vowel duration, or the difference in vowel duration is reversed from L1 Japanese speakers. Identifying the locus of the source of an L2 accent should be accompanied with intelligibility and comprehensibility. Such identification is important in increasing comprehensibility in speech that is already intelligible.