The "Type A Ko-hyoteki" (甲標的甲型 , Kō-hyōteki kō-gata , Target 'A', Type 'A') class was a class of Japanese midget submarines ("Ko-hyoteki") used during World War II. They had hull numbers but no names. For simplicity, they are most often referred to by the hull number of the mother submarine. Thus, the midget carried by "I-16"-class submarine was known as I-16's boat, or "I-16tou."