Art in North Korea is primarily didactic; cultural expression serves as an instrument for inculcating Juche ideology and the need to continue the struggle for revolution and reunification of the Korean Peninsula. Foreign governments and citizens, especially the Japanese and the Americans, are depicted negatively as imperialists; revolutionary heroes and heroines are seen as saintly figures who act from the purest of motives. The three most consistent themes are martyrdom during the revolutionary struggle (depicted in literature such as The Sea of Blood), the happiness of the present society, and the genius of the leader.