Fujiwara Seika (藤原 惺窩, February 8, 1561 - October 19, 1619) was a Japanese philosopher, a leading neo-Confucian of the early Tokugawa Period and a teacher of Tokugawa Ieyasu.
Like his student, Hayashi Razan (1583–1657), he had studied in Zen monasteries. But in 1598, at Fushimi Castle, he met Gang Hang (1567–1618), a Korean neo-Confucian scholar who was taken prisoner to Japan during Japanese invasions of Korea (1592–1598). In Joseon Dynasty, neo-Confucianism was the state ideology and there were a lot of neo-Confucianism scholars and literature. On the contrary, the academism of Japan was usually confined only in the Buddhist monasteries during the civil wars of Daimyo rivalry. And the classical Chinese, in which most of neo-Confucian literature were written, was legible only to the educated Buddhists like Fujiwara or Hayashi. Most of samurais were illiterate then. So neo-Confucianism was very fresh to Japan at that time and interesting to educated Buddhists first. Fujiwara learned neo-Confucianism from Gang Hang and became the originator of Japanese neo-Confucianism.
Later Tokugawa Bakufu adopted neo-Confucianism as ruling ideology, like Chinese and Korean dynasties. Soon neo-Confucianism in Japan was matured and many of prominent neo-Confucianists emerged during Tokugawa Shogunate period.