The March 11 disaster killed 378 elementary, junior high and high school students and left 158 others missing, the boards of education in the three hardest-hit prefectures have said.
Most of the victims left school before or just after the 2:46 p.m. earthquake and were swept away by tsunami, they said Wednesday. Students who remained in school buildings mostly survived.
If the magnitude 9.0 quake had struck an hour later, a far greater number of students could have been killed, the board in Iwate Prefecture said.
The total of 536 killed and missing students was limited to the three prefectures of Iwate, Miyagi and Fukushima and comprises 234 elementary, 111 junior high and 191 high school students.
Out of the 378 students confirmed dead, 273 were in Miyagi, 59 in Fukushima and 46 in Iwate. The list of missing students is made up of 74 in Miyagi, 52 in Iwate and 32 in Fukushima.
As of 4 p.m. Wednesday, the death toll from the disaster stood at 14,517, with 11,432 others unaccounted for in 12 prefectures, according to the National Policy Agency.
The NPA earlier said that 92 percent of the bodies examined by April 11 in the three hardest-hit prefectures were confirmed as having died of drowning. Of these victims, 65 percent were aged 60 or older, while less than 4 percent were aged 9 or under.