More than eight years have passed since the Fukushima Dai`ichi Nuclear Power Plant accident on March 11, 2011. Damaged infrastructures have been partially reconstructed, financial aid has been paid, and the preparation to the 2020 Summer Olympics in Tokyo is in full swing conveying the image of the country`s success in dealing with one of the greatest calamities in modern Japanese history. Nonetheless, imperceptible to human senses and delayed in time acts of radiation “slow violence” (Nixon, 2011) remain untelevised and underrepresented in policy-making as well as in human memory.

This paper analyses the work of the fund organized by parents, primarily mothers, to provide annual thyroid cancer screening for children from the Kanto region. Through the analysis of semi-structured interviews with Kanto region activists and physicians as well as participant observation of the fund`s activities, the paper uncovers complex hierarchies of radiation risks recognition. By drawing on the concepts of environmental (Schlosberg, 2007) and testimonial (Fricker, 2007) justice, this paper reveals how social groups that had been constantly excluded from the decision-making process and deprived of opportunities to participate in the spread and production of scientific knowledge were able to address the representational challenges of radiation pollution and counter the violence of radiation exposure risks. Furthermore, the paper enhances our understanding of environmental justice realms and sheds light on challenges inherent in citizen science.