Seida Okusu, Natural Monument camphor tree in Gamagori, Japan

Seida Okusu is a camphor tree standing alone on a fan-shaped slope near the mountains of northern Gamagori, now surrounded by mandarin orchards. It measures 22 m tall, 14.3 m around the trunk and 13.6 m around the base, with branches reaching 14.55 m east and 14.47 m south. Large burls sit on the east and south sides between 1.2 and 3.6 m above ground, and the trunk leans slightly west.

According to legend, Minamoto no Yoshiie planted the tree while departing to suppress a rebellion in Oshu. It was worshipped as a sacred tree because of a belief that damaging it would bring a fire destroying all of Seida village. It was designated a National Natural Monument on 17 December 1929; the Hachiman shrine beneath it was then merged into Ishiyama Shrine.

The tree was worshipped as a go-shinboku, a sacred tree, because of a belief that damaging it would bring a fire that burned all of Seida village; a farmer who cut the undergrowth is said to have lost his house to fire. A Hachiman shrine once stood beneath it and was merged into Ishiyama Shrine in Seida after the 1929 designation. Since 2008 the Seida Okusu Aikokai volunteers loosen compacted soil, remove stones and lay reeds over the root area.

The tree stands alone at 91 Shimoshinya, Seida-cho, in Gamagori, among mandarin orchards on a fan-shaped slope near the northern hills. It is about a 35-minute walk from Gamagori Station on the JR Tokaido Main Line and Meitetsu Gamagori Line. The trunk leans slightly west, and the ground around the roots is kept soft and covered with reeds by the Seida Okusu fan club.

In 1998 the arborist Susumu Hayashi measured the trunk at 14.3 m, 2.5 m more than earlier surveys, which made it the largest camphor tree in the Chubu region. A local fan club founded in 2008 loosens compacted soil around the roots and lays reeds to keep the topsoil from drying out.