"Crescent Moon in the Warring States" is a historical fantasy manga set during Japan's Sengoku period, blending historical events with supernatural elements. The protagonist, Mitsuki, is a modern-day high school girl who is transported back in time to the 16th century after encountering a mysterious crescent moon-shaped mark. In this tumultuous era, she becomes entangled in the lives of powerful warlords and supernatural beings, navigating the complexities of war, politics, and her own unexpected role in shaping history.

Mitsuki discovers she is the reincarnation of Princess Tsukuyomi, a figure of great significance tied to the moon and its mystical powers. Her arrival coincides with the rise of Oda Nobunaga, a ruthless and ambitious warlord seeking to unify Japan. Mitsuki's presence attracts the attention of various factions, including the warlords, yokai (supernatural creatures), and other reincarnated individuals with their own agendas. As she struggles to understand her powers and purpose, Mitsuki forms alliances with key historical figures, including Nobunaga himself, while also confronting enemies who seek to exploit her abilities for their own gain.

The narrative explores themes of destiny, loyalty, and the clash between human ambition and supernatural forces. Mitsuki's journey is marked by her efforts to reconcile her modern sensibilities with the brutal realities of the Sengoku period, as well as her growing connection to the people and events of this era. The story intertwines historical accuracy with imaginative twists, presenting a vivid portrayal of the period's chaos and intrigue. Key characters include Nobunaga, depicted as both a visionary leader and a ruthless conqueror, and Mitsuki's companions, who range from loyal retainers to enigmatic yokai. The manga balances action, political intrigue, and emotional depth, offering a compelling exploration of a pivotal moment in Japanese history through a fantastical lens.