This lesson is following the textbook Minna no Nihongo. Lesson 8.Fujisan wa Takai Desu [i adjective] There are two kinds of adjectives in Japanese. One is い形容詞 i-keiyoshi , the other is な形容詞 na-keiyoshi. When you make a negative sentence, there is a conjugation of adjective. 高い + ない = 高くない　これは　赤い　花です。