post-war high school
Refers specifically to high schools established under the post-World War II education system reform in Japan, as distinct from pre-war institutions.
彼は新制高校の一期生として入学した。
He entered as a member of the first class of the new post-war high school.
旧制高校 refers to pre-war higher schools under the old system, while 新制高校 refers to the post-war high schools.
高校 is the general modern term for high school, without the historical distinction of 新制高校.
Compound of 新制 (new system) and 高校 (high school), referring to the educational reform after World War II.