Complex sentence: Shinozaki Mamoru was a Japanese spy horrified by the actions of the Japanese military during the occupation of Singapore, he illicitly used his authority to issue many "good citizens passes" to Chinese, and Eurasian citizens, saving many from the Sook Ching massacre.
Split into simpler sentences: Shinozaki Mamoru was a Japanese spy horrified by the actions of the Japanese military during the occupation of Singapore. He illicitly used his authority to issue many "good citizens passes" to Chinese, and Eurasian citizens, saving many from the Sook Ching massacre.