In English, we have prefixes, like "pre-"; suffixes, like "-ize"; and arguably, expletives that function as infixes (one classic example is "abso-fucking-lutely").
In Japanese, we also have prefixes, like 超~, 大~; and suffixes, like ~っぽい, ~化{か}. Does Japanese have any infixes, though? I'm interested both in any modern, productive infixes that may exist that I'm not aware of, as well as any historically-productive infixes that are now fossilized.