There has been a significant interest on plasmonics in a metallic structure with very narrow gaps for studies of nanophotonics. However, little attention has been paid to the behavior of surface plasmons (SPs) in quasi-continuous metallic structures. This study observes and analyzes intermediate characteristics between propagating SPs (PSPs) and localized SPs (LSPs) in a quasi-continuous metallic monolayer of core-shell nanocubes. We reveal that, in a very narrow region of few-nanometer gaps among the nanocubes, the intrinsic energy bands of PSPs and LSPs intersect each other to generate two hybrid bands and an anti-crossing. Using a self-assembly method instead of the lithographic techniques which have several limitations as of now, we materialize the quasi-continuous metallic layer with plenty of nano-gaps that exhibit intermediate plasmonic characteristics. The intermediate plasmonic characteristics observed in this study will lead to interesting subjects, such as band engineering and slow SPs, in nanophotonics.