One of the important topics in current syntactic theory is whether there is a directionality parameter in Universal Grammar. Based on the observation that the presence of Chinese sentence-final aspectual particles blocks movement out of their complement, Lin (Complement-to-Specifier movement in Mandarin Chinese. MS., National Tsing Hua University, 2006) argues that each of these particles is the head of an underlyingly head-initial phrase and that the surface head-final order is derived by movement of its complement. Thus, movement out of it violates the Condition on Extraction Domain [CED: Huang (Logical relations in Chinese and the theory of grammar. PhD dissertation, MIT, 1982)]. Taking this analysis as a diagnostic that distinguishes a derived head-final structure from a genuine one, this paper illustrates that it is not the case that Japanese head-final structures are derived from head-initial ones. Our result implies that Universal Grammar is equipped with a directionality parameter, admitting not only head-initial structures but also headfinal structures.