The National Institute of Polar Research (NIPR) publishes Polar Science, a peer-reviewed quarterly journal dealing with polar science in collaboration with the Elsevier B. V.. The most recent issue (Vol. 27 published in March 2021) was a special issue entitled "Arctic Challenge for Sustainability Project (ArCS)," which featured the former national (nation-wide) Arctic research project in Japan. The full text of this issue is freely accessible worldwide for a limited time until 10 September 2021. The Arctic Research Project "Arctic Challenge for Sustainability (ArCS)" was carried out from September 2015 to March 2020 as a national flagship project funded by the Ministry of Education, Culture, Sports, Science, and Technology (MEXT).