"Taiyō Shijinki" is a manga series that blends elements of fantasy, action, and mythology, centering on a world where humanity faces extinction due to the emergence of monstrous beings known as Shikigami. These creatures, born from the remnants of ancient gods, possess immense power and wreak havoc on the world. The story revolves around a young man named Kōta, who becomes the vessel for Taiyō, the last remaining god. Taiyō, once a powerful deity, now exists in a weakened state and relies on Kōta to survive. Together, they form a symbiotic relationship, with Kōta gaining access to Taiyō's divine powers to combat the Shikigami.

Kōta's journey begins when he encounters a mysterious girl named Yūki, who is revealed to be a Shikigami herself but retains her human consciousness. Yūki becomes a key ally, as her unique nature allows her to resist the destructive instincts of other Shikigami. The trio—Kōta, Taiyō, and Yūki—embarks on a mission to confront the Shikigami threat and uncover the truth behind their origins. Along the way, they face numerous challenges, including powerful Shikigami leaders who seek to dominate the world and remnants of ancient human factions with their own agendas.

The narrative explores themes of coexistence, identity, and the struggle between humanity and divinity. Kōta grapples with the moral implications of wielding Taiyō's power, as it often comes at a cost to his humanity. Yūki's dual nature as both Shikigami and human adds complexity to her character, as she struggles to reconcile her instincts with her desire to protect others. Taiyō, though initially portrayed as a detached and enigmatic figure, gradually reveals a deeper connection to the world and its fate.

As the story progresses, the characters uncover secrets about the ancient war between gods and humans, which led to the creation of the Shikigami. This history intertwines with their present struggles, revealing that the conflict is far more intricate than it initially appears. The manga balances intense action sequences with moments of introspection, delving into the characters' motivations and the broader implications of their actions. The interplay between Kōta, Taiyō, and Yūki drives the narrative forward, creating a dynamic and engaging storyline.