I know that Japanese consists of 3 writing systems that work together, but Japanese still uses alot of Chinese characters in it's language, how did the Japanese feel about this during world war two?
Technically all three "alphabets" (hiragana, katakana, and kanji) are derived from Chinese characters.
Simply put, they didn't care. The reason Japan attacked China wasn't because of some fear of Chinese influence or culture-it was due to what was perceived as unprovoked insults or aggression against Japanese interests (which were caused by Japanese imperialism, but that didn't make it to the Sunday Yomiuri). The war was perceived as both a war to "punish" the Chinese as well as to restore order in what was thought to be an an anarchic and fractured country.