かあ カー きい キー くう クー こう（こお） コー

The long “ee” and “oo,” as in combinations, けえ and こお, occur in only a few words. They must be learned individually.

The bar used to indicate the long vowels in katakana must be written horizontally when you write sentences horizontally. When you write sentences vertically, however, the long vowel bars must also be vertical. These bars must be written in the center of space.