Kolej Tuanku Ja'afar (KTJ), is a co-educational international school in Mantin, Seremban District, Negeri Sembilan, Malaysia, founded in 1991. Its Primary School is a day school for pupils between the ages of 4 and 11 while its Secondary School offers boarding for students from the age of 11 to 19. Day schooling is also possible in the Secondary School. It is a British curriculum school.