Suwa-daijin, Shinto shrine in Tonosho, Chiba Prefecture, Japan

Suwa-daijin is a small Shinto shrine in Tonosho with modest wooden structures and a simple layout. The site is surrounded by trees, features well-maintained grounds, and contains small offerings such as coins, flowers, and personal items left by visitors.

Tradition credits Sakanoue no Tamuramaro with founding the shrine's first small sanctuary while praying for the defeat of malevolent deities during the subjugation of the Emishi; it is said to have been built in 807 (Daidō 2) and was also called Sugayama Myōjin. Ōe no Koretoki had the shrine buildings constructed, and in 1191 (Kenkyū 2) Minamoto no Yoritomo ordered Higashishige Tane to rebuild them. Tokugawa Ieyasu donated 10 koku of tax-exempt land in 1591, and in 1718 the shrine received the senior first rank.

The shrine's spring festival features "Sasakawa no Kagura" at the kagura hall, a cycle of sixteen dances with masks such as the tengu, the small-roof deity, Otama no Mikoto, the maiden and Tajikarao, also called Daidai Kagura or Iwato Kagura and designated an intangible folk cultural property of Chiba Prefecture. The autumn festival centres on a sumo tournament, with floats parading through the streets and an amateur sumo contest held since Sasakawa Shigezo organised it.

The shrine is a five-minute walk from JR Sasagawa Station on the Narita Line. The grounds also hold the Nomino Sukune monument, erected in 1842 by Sasagawa Shigezo, and the Tenpo Suikoden relics hall stands at the entrance. The spring festival's Kagura is performed in the kagura hall before the deities.

In the grounds stands a stone monument to the wrestler Nomi no Sukune, erected in 1842 by Sasagawa Shigezō, the local boss who also started the autumn sumo tournament. At the entrance, the Tenpō Suikoden relic hall keeps material on him. During the 2017 summer sumo tour, wrestlers of the Dewanoumi stable ranked below makuuchi lodged here for training.