Final answer:
In the short story 'The Garden of Forking Paths' by Jorge Luis Borges, Dr. Yu Tsun is working for the Germans.
Step-by-step explanation:
In the short story 'The Garden of Forking Paths' by Jorge Luis Borges, Dr. Yu Tsun is working for 1) The Germans. The story is set during World War I, and Dr. Yu Tsun, a Chinese man, is a spy for the Germans, providing them with valuable information regarding the positions of the British army. His mission is to convey this crucial information to his German contact, Captain Richard Madden.