Im struggling to understand why Hitsuyou (ひつよう) is considered a な adjective.
From what I understand after reading about い adjectives we simply drop the last い to make it negative, for example: さむい becomes 住むくない because we dropped the last い and added くない to make cold become "not cold".
This is pretty simple to understand as each word we want to make negative usually has an い on the end.
However, using this same rule to use じゃない for な doesnt make sense to me with ひつよう as there is no な in the word.
Ive been reading through this online dictionary but still haven't been able to grasp why.
Can you help me understand?