Research in contrastive linguistics is noteworthy as it provides valuable observations that can be applied in foreign language education and as it allows shared theories attested in the languages under comparison. The current study compares the various accounts for the double-subject construction, which has received much attention in Korean and Japanese linguistics, and attempts to reveal their fundamentals. The existing theories on the phenomenon in the two languages have so far been overall compatible in terms of macro-micro subject theory, predicate clause theory, and topicalization theory. Nevertheless, the current paper offers critiques on `additional/vicarious function`(`兼務`/`代行`) that Mikami(三上) defended in 「zou-wa hana-ga nagai(象は鼻が長い)」. Additional/ vicarious function of topic marker {wa}(nun) argues that the nominative, accusative, locative, dative, and genitive case markers have. However, this is a misinterpretation caused from the omission of the case marker that follow {wa}(nun) as a result of topicalization. Topic markers cannot be argued to substitute the roles of other case markers.
