Suicides fell for a sixth consecutive year in 2015, dropping 5.5 percent from the previous year to 24,025, the National Police Agency said Friday.
Suicides related to the March 2011 earthquake, tsunami and nuclear crisis came to 23, up from 22 in 2014, with 19 of them occurring in Fukushima Prefecture alone, police data showed.
Of the remainder, three were reported in Iwate Prefecture, and one in Miyagi.
It is the first time that suicides in Fukushima have accounted for more than 80 percent of all disaster-linked suicides.
The deaths reflect the effects of the prolonged evacuations triggered by the triple core meltdown at the Fukushima No. 1 nuclear power plant, government officials said.
"People becoming distressed or isolated at places they evacuated to could be a cause" of the suicides, a Cabinet Office official who analyzed the data reckoned.
Grouped by age, people in their 70s accounted for the largest portion of suicides at seven, followed by five in their 60s and four in their 40s and 80s. One person was aged in the 20s, the data said.
Thirteen killed themselves over health issues, while six cases involved family problems, according to the data.