Now when we are trying to say Sotto, how can this be written in Hiragana? So-t-to, but there is no character for just a "t". To do this, we add a small "tsu" character before the "to" to make a so-t-to. This rule is used for every combination except for "N" which is just a repeat of itself.
Long vowels are used for when writing Hiragana. The II is written just the same as you would expect, although for EE, you would have to write it as EI even though it is still sounded the same. This rule also applies to UU as it is written as expected but OO is written as OU.
