Motoyama Shigetoki served as a bushō during the Sengoku period.  He was the head of the Motoyama clan who were one of the seven gōzoku, or wealthy families, in Tosa Province known as the Tosa shichiyū from the latter part of the Muromachi period to the Sengoku period.

In 1525, Shigetoki was born as the eldest son of Motoyama Shigemune, a daimyō and head of the Motoyama clan residing in the Motoyama township in Tosa.

The Motoyama had a contentious relationship with the Tosa-Ichijō family and decided to attack the Tosa-Kira clan who were aligned with the Ichijō.  In 1540, the Motoyama took advantage of an opportunity to attack while Kira Nobunao, the head of the Kira clan, was away hunting on the Niyodo River.  The Motoyama divided into two units.  Shigetoki led one of the units to Kiramine Castle and, in the absence of its lord, proceeded to topple it.  The other unit headed toward the Niyodo River and killed Nobunao, thereby eliminating the Tosa-Kira clan.

In 1555, following the death of Shigemune, Shigetoki succeeded him as the head of the clan based at Asakura Castle in the central plains district.  Shigetoki had from earlier times been opposed to Ichijō Kanesada and, on 2/25, felled Hasuike Castle in the Takaoka District.  From 1556, however, Chōsokabe Kunichika (his father-in-law) began a revolt so conflicts persisted between Shigetoki on one side and Kunichika, together with his son, Chōsokabe Motochika, on the other.  In the fifth month of 1560, at the Battle of Nagahama, the Motoyama suffered a major defeat to the Chōsokabe.  In the sixth month, the Motoyama lost Urado Castle and holed-up in Asakura Castle.  Thereafter, Motochika soon toppled outlying castles built to defend the main base at Asakura.  In the third month of 1561, the Motoyama were attacked and lost.

In the ninth month of 1562, the Motoyama incurred another attack by Motochika but prevailed in part through the efforts of Shigetoki’s son, Motoyama Sadashige (later known as Chikashige).  The Motoyama army, however, sustained significant losses, and, thereafter, owing to scheming by the Chōsokabe, the gōzoku under the command of the Motoyama gradually began to switch their loyalties.  On 1/10 of Eiroku 6 (1563), Shigetoki abandoned Asakura Castle and pulled back to Motoyama Castle in the mountainous areas.  In the fifth month, Shigetoki attempted a comeback by attacking Okō, but was defeated.  In the fourth month of 1564, he departed Motoyama Castle to hole-up in Unryūno and resist.

Shigetoki is said to have died of illness at the height of this battle, but the only basis for this conclusion is that his name no longer appears in historical materials, whereas there are no authenticated sources regarding the date and location of his death so, in fact, his whereabouts after this time are unknown.

Meanwhile, historical accounts of the Chōsokabe compiled toward the end of the Tenshō era (1573 to 1593) more than twenty years after 1564 refer to an individual under the name of Motoyama Taifu-Hōshi-dono.  After Shigetoki’s son, Sadashige, surrendered to the Chōsokabe and became a retainer, only lineal heirs of the Motoyama clan were referred to with the title of “dono.”  Sadashige’s siblings are referred to separately so the stated name could only have been in reference to Shigetoki from the previous generation.  This gave rise to a theory that Shigetoki entered the priesthood and resided under the protection of Chōsokabe Motochika.  Under this theory, it is surmised that Shigetoki surrendered and entered the priesthood in exchange for having his life spared, but his wife (Motochika’s older sister) and retainers backed Sadashige and continued resistance against the Motoyama.