Imperial Prince Morinaga (1308-1335), the third son of Japanese Emperor Go-Daigo, was one of the prime movers behind the overthrow of the Kamakura Shogunate and his father's resumption of direct Imperial rule in the "Kemmu Restoration". While Go-Daigo spent most of his time fleeing from enemies or in exile, Morinaga tirelessly traveled the countryside, building armies, raising money, forging alliances, and fighting battles in his father's name.
Morinaga was born Prince Oto-no-miya Morinaga in 1308 to longtime Imperial consort Minamoto no Chikako, who had also been a consort to Go-Daigo's father (Morinaga's grandfather). When Morinaga was just 18, Go-Daigo contrived to have him named the head abbot of the powerful Enryakuji temple on Mount Hiei, thus securing the loyalty of Enryakuji's mighty army of warrior monks.
When Go-Daigo's second plot to overthrow the Kamakura Shogunate was crushed in the Genkô Incident of 1331, Go-Daigo was deposed and exiled to distant Oki island, and Morinaga was forced to flee Enryakuji for the wild mountains of Kii province far to the south. There, he met up with one of the last holdouts of the Imperial loyalists - the minor warlord Kusunoki Masashige. Together, they defended the small fortress of Akasaka against overwhelming odds, exacting a heavy toll on the Shogunate's troops before they were finally forced to withdraw.
While Masashige was setting up a new fortress at Chihaya, Morinaga set up an Imperial headquarters at Mount Yoshino. He sent out a general call to all warriors to rise up against the Shogunate and restore Go-Daigo to his rightful throne, and devoted himself to rallying nearby warriors and landholders to the Loyalist cause. Together, Masashige's daring stand at Chihaya against an even larger Shogunate assault and Morinaga's powers of persuasion inspired a large number of warriors to join the revolt, and the Shogunate was finally overthrown when two powerful eastern warlords - Ashikaga Takauji and Nitta Yoshisada - joined the fray on the side of the loyalists.
After Go-Daigo was restored to the throne in 1333 and began the first direct Imperial rule of Japan in nearly 400 years, he named Prince Morinaga, whom he trusted beyond all his other warlords, to the post of shogun, thus giving Morinaga supreme authority over all Imperial forces. This move greatly embittered Takauji, who felt he should have been given the title of Shogun since he had contributed the largest number of warriors to the Imperial cause.
Takauji soon trumped up some false charges alleging that Morinaga was ploting against his own father Go-Daigo, and pressured Go-Daigo into handing over Morinaga into Takuji's custody as a prisoner. Takauji then dispatched Morinaga to Kamakura, where his brother Tadayoshi had established his headquarters. Tadayoshi had Morinaga kept prisoner under constant guard in a cave in the hills near Kamakura for eight months, before finally taking advantage of the confusion and chaos of an attack by one of the last heirs of the overthrown Kamakura Shogunate to have Morinaga quietly beheaded.
The year was 1335, and Morinaga was barely 26 years old.
In later years, Morinaga was memorialized as an epitome of filial piety who sacrificed everything for his father's happiness, fighting in the trenches, performing lowly tasks far below his station, and ultimately giving up his very life. In 1869, a Shinto shrine to Morinaga's spirit, the "Kamakuragu," was constructed in Kamakura near the cave where he died.