Veterans Day is right around the corner. Familysearch.org has three databases that those researching in Hawaii will find useful.
Be sure to click Draft Registration (next to birth) and enter Hawaii to limit your results.
You can define by birth, residence, or branch of the military if you know it.
This is nicknamed the “old man draft”. It includes people born 1877-1897.
Now got out and give your veteran relatives some love by finding their records.