Complex sentence: When Susuki visits Sudou's apartment, she plays an instrument he made, which transports Sudou to the year 1209, where he awakes to find he is now a woman nicknamed Shut Hell and Susuki a Mongol prince named Yurul.
Split into simpler sentences: When Susuki visits Sudou's apartment, she plays an instrument he made, which transports Sudou to the year 1209. He awakes to find he is now a woman nicknamed Shut Hell and Susuki a Mongol prince named Yurul.