The number of single-sex schools in Japan has dropped by half in the last 20 years to its lowest point ever, according to a 2011 survey by the Education, Culture, Sports, Science and Technology Ministry. In 1989 at the start of the Heisei era, there were 1,002 single-sex high schools nationwide.
As of 2011, only 464 such schools remained, accounting for only 9.2 percent of all schools.
A large part of the reason for the change is the shrinking numbers of students. Schools are heavily dependent on entrance exam fees as a source of funding, so becoming coed opens up the possibility of more exam takers, as well as more students. A more fundamental reason, though, is that parents and educators see coeducation as a positive learning environment for students.