"Angolmois: Record of Mongol Invasion" is a historical anime set in 13th-century Japan during the Mongol invasions. The story centers on the island of Tsushima, a strategic location between the Korean Peninsula and mainland Japan. As the Mongol Empire, led by Kublai Khan, seeks to expand its dominion, Tsushima becomes the first line of defense against the impending invasion. The narrative begins with the arrival of exiled samurai Jinzaburou Kuchii, who is sent to Tsushima as punishment for his involvement in a failed rebellion. Despite his initial reluctance, Jinzaburou becomes a key figure in organizing the island's defense against the overwhelming Mongol forces.

The plot unfolds as the Mongols, equipped with advanced weaponry and tactics, launch a brutal assault on Tsushima. The island's inhabitants, including local warriors, farmers, and refugees, must band together under Jinzaburou's leadership to resist the invaders. The story highlights the stark contrast between the Mongols' organized, large-scale warfare and the fragmented, resource-limited resistance of the Tsushima defenders. Key characters include Teruhi, the strong-willed daughter of the island's ruling clan, who plays a pivotal role in rallying the people, and Onitakemaru, a fierce warrior with a personal vendetta against the Mongols.

The series delves into the complexities of warfare, survival, and the human cost of conflict. It portrays the desperation and ingenuity of the defenders as they employ guerrilla tactics and makeshift strategies to counter the Mongol onslaught. The narrative also explores themes of loyalty, sacrifice, and the clash of cultures, as the people of Tsushima face not only external threats but also internal divisions and moral dilemmas. The historical backdrop provides a gritty, realistic portrayal of the Mongol invasions, emphasizing the brutality and chaos of the era while staying grounded in the experiences of its characters.