Prince Morinaga, also known as Prince Moriyoshi and Son of Emperor Daigo II, was a Japanese prince and monk. He is still worshipped today at Kamakura-gū, a shrine founded on the site of a Buddhist temple where he was once imprisoned and executed. 

Morinaga was a fierce samurai who led an army against and successfully overthrew the military government of the Kamakura shogunate in 1333, re-establishing Imperial rule for his father.

The Emperor, however, favored the samurai clan of Ashikaga over his own son, suspecting him to be a would-be usurper and exiling him for his strong distrust toward the Ashikaga clan. After being imprisoned in a small dungeon for ten long months at 28 years old, Prince Morinaga was murdered by an assassin sent by the clan.

According to the Taiheiki, a chronicle written in the 14th century, the Prince struggled hard against the assailant, biting off the tip of his sword. Even after he was decapitated, his lifeless head glared at his murderer and ground his teeth on the broken blade. Terrified, the assailant is said to have thrown the Prince's head away into the woods.

With the death of Morinaga, the Emperor's army grew weaker and weaker, and as he had predicted, the Ashikaga clan came to rise to power. Only three years after the Restoration, the new Imperial government was overthrown and replaced by another shogunate: thus began the Muromachi period.

Today, the (purpoted) site of Prince Morinaga's Dungeon can be found at the back of Kamakura-gū Shrine, restored as an eerie grotto-prison with wooden bars. Somewhat hidden, yet not quite forgotten, locals continue to visit the site to pay respect to Morinaga to this day.