IntroductionIt is a well-known fact that tense, aspect and mood/modality (TAM) are encoded in morphosyntactically diverse ways across languages. Some languages realise them purely by verb inflectional morphology, while others express them periphrastically by a verb and auxiliary/copula complex. Since Japanese is one of the languages that exhibit a combination of those two strategies in rather complicated manners, it poses a serious challenge to any grammatical theory as to how lexical verbs, auxiliaries, copulas, particles and inflectional suffixes are located in morphosyntactic structures, and how they are related to TAM functions in relevant components of the grammar. In the frameworks that place syntactic derivation in the central component of the grammar such as Minimalist Program and its variant, particularly in the recent development of syntactic structure above the proposition level (Rizzi 1997, Cinque 1999, it is assumed that mood suffixes head Fin(ite) or Mood projection and modal expressions and sentence final particles head Mod(al) or Force projection above T(ense) and Asp(ect) (Hasegawa 2009, Endo 2007. Lexicalist frameworks, on the other hand, maintain the division between word-internal and word-external structures. TAM realisation below V 0 -level, therefore, are operated