"Seven Day Princess" is a fantasy romance manga that centers on the life of Yui, a high school girl who unexpectedly becomes entangled in a supernatural contract. After a tragic accident, Yui is given a second chance at life by a mysterious entity known as the "Prince of Death." In exchange for seven more days to live, she must fulfill a series of tasks. These tasks are designed to test her resolve, morality, and emotional strength, as she navigates the complexities of her relationships and the consequences of her choices.

The narrative explores Yui's interactions with the Prince of Death, who remains enigmatic and detached, yet gradually reveals a deeper connection to her past. As Yui completes each task, she uncovers fragments of her own memories and the truth behind her untimely demise. The story delves into themes of sacrifice, love, and the value of life, as Yui grapples with the fleeting nature of her borrowed time and the emotional toll it takes on those around her.

Key characters include Yui, whose determination and compassion drive the story forward, and the Prince of Death, whose motives and true identity remain shrouded in mystery. Supporting characters, such as Yui's friends and family, play significant roles in shaping her journey, highlighting the impact of her decisions on their lives. The plot unfolds through a series of emotional and suspenseful moments, blending elements of romance, fantasy, and drama to create a compelling narrative. The seven-day countdown serves as a constant reminder of the stakes, adding tension and urgency to Yui's quest for redemption and understanding.