An NHK survey shows more than half of people who have suffered sexual violence have symptoms like those of post-traumatic stress disorder, or PTSD.
The survey, conducted online in March and April, gathered answers from over 38,000 respondents who say they themselves or their relatives have suffered sexual violence.
Experts analyzed the replies of more than 35,000 people who say they had been sexually abused.
The experts found that diagnoses of PTSD under international criteria are strongly suggested for more than 19,000 of the respondents, or 54.1 percent.
They also looked at the number of cases of PTSD based on the period of time that passed after the respondents had been assaulted.
The results show that the percentage of those suspected of having PTSD is 71.8 percent after less than one year, and 66.2 percent after less than three years. The percentage is still high at 48.7 among those who said they had been abused more than 20 years ago.
Clinical psychologist Saito Azusa, an associate professor of Mejiro University, says the impact of sexual violence is diverse, and that it's impossible to measure everything numerically.
She points out that the results still show the serious psychological impact such violence may inflict. She stresses it is a pressing need to prepare systems to support those who have suffered damage, as well as to train specialists who can offer such care.