In Japanese, these are all possible sounds in the language. Each is represented by 1 kana character.

a i u e o
ka ki ku ke ko
ga gi gu ge go
sa shi su se so
za ji zu ze zo
ta chi tsu te to
da ji zu de do
na ni nu ne no
ma mi mu me mo
ha hi hu he ho
ba bi bu be bo
ra ri ru re ro
ya yu yo
wa wo
n

Note that "hu" is often romanized as "fu", but in JSL it is written "hu". The actual sound is in between.