"Ashi-Girl" is a historical comedy manga set in Japan's Heian period, blending elements of romance, humor, and time travel. The protagonist, Tamaki Shinobu, is a modern-day high school girl who accidentally travels back in time to the Heian era after falling into a well. Upon arrival, she is mistaken for a noblewoman due to her unusual appearance and demeanor. To survive in this unfamiliar world, Shinobu adopts the identity of Lady Ashi, a fictional noblewoman, and navigates the intricacies of Heian court life.

The story revolves around Shinobu's efforts to adapt to her new environment while maintaining her secret. Her modern knowledge and unconventional behavior often clash with the rigid customs of the Heian period, leading to humorous situations. Despite her struggles, Shinobu's resourcefulness and quick thinking help her gain the trust and admiration of those around her, including the enigmatic and handsome nobleman, Fujiwara no Yukinari. Their relationship evolves from initial skepticism to mutual respect and affection, forming the core of the romantic subplot.

Throughout the series, Shinobu encounters various historical figures and cultural elements of the Heian period, providing a blend of educational content and entertainment. Her interactions with the court's aristocracy, servants, and even supernatural entities highlight the stark contrasts between her modern sensibilities and the traditions of the past. The manga balances lighthearted comedy with moments of tension, particularly as Shinobu's true identity is occasionally at risk of being exposed.

The narrative also explores themes of identity, cultural adaptation, and the clash between tradition and modernity. Shinobu's journey is not only about surviving in a different era but also about understanding and appreciating the values and customs of the Heian period. The series concludes with Shinobu facing the ultimate decision of whether to return to her own time or remain in the past, adding a layer of emotional depth to the story.

The main characters include Tamaki Shinobu, whose wit and determination drive the plot; Fujiwara no Yukinari, the nobleman who becomes her love interest; and a supporting cast of historical and fictional figures who contribute to the rich tapestry of the Heian court. The manga's blend of historical accuracy, comedic elements, and romantic development makes it an engaging read for fans of both historical fiction and lighthearted storytelling.