Takeda Shingen (1521-1573) was the daimyo of the Takeda clan. His father, Takeda Nobutora, had unified the province of Kai in Japan. However, in a dispute over the succession, Nobutora was driven from Kai by his twenty year old son Shingen.

From this time until his death, Lord Shingen was involved in the continuing national struggle for dominance known as the Warring States Period.

He was constantly harassed in the north by Uesugi Kenshin, and in the west by the combined forces of Oda Nobunaga and Tokugawa Ieyasu. His battles with Uesugi at Kawanakajima are particularly famous.

In 1551 he shaved his head and received a lay ordination in Soto Zen Buddhism. His rival Uesugi did the same in 1552.

Shingen was reknowned as a tactician, administrator, diplomat, and warrior. He relied on his judgement of individuals' abilities and alliances rather than on castles and fortifications. A verse of his reads:
"Men are your castles, men are your walls. Friendship is your ally, enmity your foe." A collection of sayings attributed to Lord Shingen, the "Iwamizudera Monogatari", is still deeply studied.

In 1571, Lord Shingen answered the summons of the Ashikaga shogun Yoshiakira and formed an alliance with the Asai and Asakura clans and the monks of the Pure Land Buddhist Hongan-ji line in order to move against the forces of Oda Nobunaga.

In 1573, in the midst of this campaign, he was struck by a bullet and died a few days later.

This formed the historical basis for Akira Kurosawa's film Kagemusha.