This article comprises two parts. The first is devoted to reconstructing the process in which young Taiwanese were gradually drawn into Japan's was effort. Two months after Marco Polo Incident, Japanese colonial government in Taiwan began to recruit Taiwanese as military porters and interpreters to serve the Japanese military on Chinese mainland. Later on in 1942 the so-called "Army Volunteer" came into existence, which recruited yearly. The following year witnessed the implementation of the "Navy Volunteer System." Finally in early 1945 general conscription was implemented in Taiwan. By the end of the war, Taiwanese serving in the military totaled 207,183, among whom 80,433 were regular military men and 126,750 were military employees. In the early period of the Sino-Japanese War, Taiwanese military porters and employees were sent to Central and South China. After the break of the Pacific War, may Taiwanese went to Southeast Asia (commonly known as Nan'yo at that time) to fight for Japanese Empire. Some were dispatched as far as Rabaul in New Britain and the Solomon Islands. Their number was in total 61,591. The second part of this article describes how Taiwanese fought in Southeast Asia during the Pacific War. After the war ended, Taiwanese who scattered all over Japan's fronts experienced very different home-returning. Those who came back from the Hainan Island went through the most terrible ordeal. Taiwanese veterans suffered the loss of Japanese nationality and the confusion of national/cultural identity. They are the biggest losers in the postwar transition.