MicroRNA is a short non-coding RNA whose primary function is supposed to be post-transcriptional regulation of mRNAs. Although it has been extensively studied for over a decade, its detailed mechanisms have not yet been fully understood. The difficulty is possibly because of lack of experimentally and theoretically effective methods, and this should be solved by invention of new technologies. Thus, any new proposals regarding them are welcomed. In addition to these, many new aspects, e.g., coordinated actions of microRNA with various epigenetic factors, including promoter methylations, histone modifications, and structures of chromosome, have started to pique researchers’ interests. Furthermore, non-canonical functions, e.g., functionalities inside nuclei and non-canonical bindings, also seem to be important. In conclusion, any research papers about new theoretical, computational, or experimental methodologies, as well as excellent reviews regarding these topics are welcomed. MicroRNA regulations, of not only target genes, but also any pathways, diseases, or differentiation, are also interesting topics. We are looking forward to receiving many submissions from outstanding expert on these topics.