Microplastics, an increasingly widespread environmental problem, have built a high profile on different communication platforms in Japan. Inspired by Davies and Horst’s understanding that science communication is constitutive and material, this article empirically analyzed the general situation of microplastics communication in the Japanese context. We examined the development in the meaning of microplastics as the exemplification of the constitutive dimension, as well as its communication stages, authorship, and readership with different interests as the representation of the material dimension. We chose the database National Diet Library Online as representative of Japanese literature. We extracted 190 microplastic-relevant journal articles published in different journal types from 2016 to 2020 and collected 162 online news articles as supplementary material. We found that even though the constitutive meaning of microplastics grew up fast, especially around 2018 and 2019, material factors varied that showed inclinations in practical communications. Despite the similar scale of communication in the specialist and the popular stages, the influences of scientists and interests from scientific fields on microplastics topics were overwhelmingly over the public fields, the divergences of which suggested several difficulties in solving such a complicated environmental problem.
