while japanese features consonant gemination, there are some limitations in what can be geminated. most saliently, voiced geminates are prohibited in native japanese words. this can be seen with suffixation that would otherwise feature voiced geminates. for example, japanese has a suffix, || that contains what calls a "floating mora" that triggers gemination in certain cases (e.g. || +|| > 'a lot of'). when this would otherwise lead to a geminated voiced obstruent, a moraic nasal appears instead as a sort of "partial gemination" (e.g. || + || > 'splashing').