Shiryokaku Fort is a National Historic Site located in Jinkawa-cho, Hakodate City, Hokkaido. The name comes from its four-pointed shape like a butterfly. In 1868, the Ezo Republic (Hakodate Government) occupied Goryokaku Fort, but was obliged to retreat, being attacked by the Imperial government forces. Shiryokaku was a Western-style fort, which was constructed for the back defense of Goryokaku. It was built on the hill, from which the rebellion forces could command a view of Hakodate, the main battle field of the time. Under the direction of Keisuke Otori and Captain Brunet, it was constructed only in two weeks by mobilizing 200 fugitive soldiers and 100 local people. However the fort fell only in a few hours by the full-scale attack of the Imperial forces. At the present time, the site of the ruin is arranged into a park and only the restored earthworks remain.