Ikema has 4 common vowels. However, the 'e' and 'o' are very restricted in their use.
Ikema has 18 consonants.
Interestingly, Ikema has a very rare phonetic feature. Its voiceless /n̥ / carries its own mora and only preceeds other nasals.
More detailed information is available here:
Hayashi, Yuka. "Ikema (Miyako Ryukyuan)." An Introduction to Ryukyuan Languages (2010): 167-188.