Copper alloy. According to official website of Kochi University, the commemorative coin for the 50th anniversary of Kochi University is made of copper alloy and was issued on April 20 16/day to commemorate its 50th anniversary. The front design of this commemorative coin is the symbol of Kochi University, Anyimen, and the back design is the campus scenery of this school. The commemorative coin has a face value of 50 yen, a diameter of 38mm and a weight of 4.9g g.