Japanese adjectives conjugate to become adverbs. We can change I adjectives that end with syllable I, such as HAYAI (early), to adverbs by changing the final I to KU. So, HAYAI becomes HAYAKU.

Co-ordinating units of writing must all be of the same grammatical kind. This is what is referred to as preserving parallel structure. For instance, nouns must match with nouns, adjectives with ...