"Baby Princess 3D Paradise 0 [Love]" centers around Yōtarō, a high school student who discovers he has 19 sisters after being reunited with his biological family. The story begins when Yōtarō, who had been living alone, is invited to live with the Amaha family, a large and wealthy household. Upon arrival, he learns that his mother, who had remarried multiple times, has 19 daughters, each with distinct personalities and ages ranging from toddlers to young adults. The sisters are organized by birth order, from the eldest, Sakuya, to the youngest, Haruka.

The narrative explores Yōtarō’s adjustment to his new life, navigating the dynamics of a household filled with sisters who each have their own quirks and interests. The sisters are divided into groups based on their ages and roles within the family, such as the older sisters taking on more responsibility while the younger ones are more carefree. Yōtarō’s presence disrupts the family’s routine, as his sisters vie for his attention and affection in various ways, leading to comedic and heartwarming situations.

Key characters include Sakuya, the mature and responsible eldest sister who acts as a maternal figure; Miharu, the second sister who is cheerful and outgoing; and Haruka, the youngest, who is playful and innocent. Each sister has a unique relationship with Yōtarō, ranging from protective to flirtatious, reflecting their individual personalities. The series balances lighthearted comedy with moments of familial bonding, as Yōtarō gradually becomes an integral part of the family.

The plot is episodic, focusing on Yōtarō’s interactions with his sisters in everyday scenarios, such as family outings, school events, and household chores. These interactions highlight the challenges and joys of living in such a large family, emphasizing themes of love, acceptance, and the importance of familial bonds. The series concludes with Yōtarō fully embracing his role as the brother of 19 sisters, solidifying his place within the Amaha family.