When writing a composition, when do you use a sequence of simple sentences, and when do you use a single complex sentence instead? Grammarians have yet to clarify the norms for determining which option to choose. In this presentation, we argue that when it comes to the interchangeability of a complex sentence with a sequence of simple sentences, there is asymmetry between statements of cause/reason and those featuring a contrastive conjunction. We also argue that in the case of lengthy complex sentences, Japanese, unlike Chinese, actively uses non-restrictive noun phrase modifiers to avoid a linear sequence of adverbial (dependent) clauses.