You accidentally made 2 threads so I deleted the other one. Here is pm215's answer from that thread.
pm215[/quote Wrote:That is a "small tsu", which is a half-size tsu used to indicate what in romaji is written using a doubled consonant, as in 'ippai'; a full size tsu would be 'itsupai' if such a word existed. Other small kana are used in writing sounds like kya, kyu, etc. Check your hiragana reference, it should explain this stuff.