This paper investigates verb reduplication (VR) in Japanese, focusing on three key properties: (i) the obligatory insertion of the light verb su, (ii) iterative aspectual meaning, and (iii) total reduplication of the verbal stem. Drawing on the framework of Distributed Morphology, I argue that VR is mediated by an aspectual head (Asp) that projects between vP and VoiceP. This head simultaneously blocks head movement (triggering su insertion), introduces the iterative aspectual feature, and undergoes morphological reduplication via a RED morpheme. The analysis accounts for the syntactic, semantic, and morphophonological properties of VR and extends to related constructions like hito-V compounds. The findings contribute to our understanding of aspectual morphology and the interaction between syntax and morphology in Japanese.
Takayuki Akimoto (Mon,) studied this question.