Human rights in Japan have improved in some areas, the U.S. State Department said Thursday in an annual survey of nations worldwide, but it listed a slew of failings that remain unaddressed.

Among the improvements, the department's 2015 Country Reports on Human Rights Practices noted reductions in the use of solitary confinement in prisons and an increase in the recording of interrogations by police and prosecutors.

However, it pointed to persistent problems such as poor conditions in prisons and detention centers and the sexual exploitation of teenage girls.