<p>In Japan, native Wu Tou is used in place of Fu Zi. In ancient times Wu Tou was stronger than the present Wu Tou. Li Shizhen says, &ldquo;It&rsquo;s rare to find Wu Tou that weighs one Liang. Wu Tou that weighs over half a Liang is still good quality.&rdquo; In terms of weight and effectiveness, Wu Tou in Japan is almost identical to that mentioned by Li Shizhen.</p>

<p>The Bo Wu Zhi says, &ldquo;Wu Tou, Fu Zi and Tian Xiong are the same thing.&rdquo; The Guangya says, &ldquo;Fu Zi one year old is called Ce Zi. Fu Zi two years old is called Wu Hui. Fu Zi three years old is called Fu Zi. Fu Zi four years old is called Wu Tou. Fu Zi five years old is called Tian Xiong.&rdquo; Although Fu Zi can be divided into many types, they&rsquo;re all the same in terms of effectiveness. Fu Zi should be grated before use.</p>
