This chapter attempts to argue that, in accounting for the distribution of case particles in Japanese, the theory of morphological case (Marantz, ESCOL ’91, 234–253, 1992, Baker, Case: Its principles and parameters, Cambridge University Press, 2015) should be preferred over the theory of Case valuation as a reflex of ϕ-feature agreement (Chomsky, Ken Hale: a life in language, MIT Press, 2001, Fundamental issues in linguistic theory: essays in honor of Jean-Roger Vergnaud, MIT Press, 2008). An ordered set of rules of morphological case marking is proposed in such a way as the dative -ni as inherent case is assigned first, then followed by the accusative -o as dependent case, and further followed by the nominative -ga as unmarked case. Additionally, it is suggested that some occurrences of the dative -ni as in the ditransitive case array (nominative-dative-accusative) are the realization of dependent ergative. Finally, it is also proposed that the domain for dependent case assignment in Japanese is the complement of a phase head, that is, VP and TP.