
So, to write the popular word "arai" (What?), first write the "O" to announce that the next letter is going to be a vowel, then the letter "a". The next vowel "ai" happens to be put in front of the consonant which it actually follows, the letter "r", thus in effect writing "oaair" and pronouncing it "arai". (Come and think of it decades later, it now looks as if the rule of preceding a vowel by the letter "O" does not apply to the vowel "ai" . . . )
Enuf already!