TV-Series
Description
Fukaboshi, also known as Shark Star, is the first prince of the Ryugu Kingdom and the eldest son of the Neptune royal family of Fish-Man Island. As a shark merman, his imposing physical stature is immediately noticeable. He possesses a muscular, towering frame that stands at 604 centimeters, more than twice the height of an average human. His appearance includes the distinct features of a shark, such as sharp, jagged teeth and gill slits on his neck, alongside wavy, shoulder-length light blue hair and a dot on his forehead. The lower half of his body is a powerful fish tail with light blue, polka-dotted patterns, and he typically carries a golden trident as his weapon of choice.

In terms of personality, Fukaboshi is characterized by a deep sense of responsibility, calmness, and a serious demeanor befitting his role as the crown prince. He frequently serves as the voice of reason and the primary speaker among his three brothers. Despite his royal status, he is known to be polite, thoughtful, and forgiving, as seen when he apologizes to mermaids who hid the Straw Hat Pirates after realizing they were not a threat. He approaches crises with logic and a level head, such as when he negotiated with Roronoa Zoro during a hostage situation at the palace. While he is generally composed, he possesses a fierce temper that surfaces when his family or his mother's legacy is disrespected, brutally defeating an enemy who forced citizens to trample on a portrait of the late Queen Otohime.

Fukaboshi's motivations are almost entirely shaped by the life and tragic death of his mother, Queen Otohime. He witnessed her assassination ten years before the main story, an event that forged his unwavering resolve to fulfill her dying wish. She implored her sons not to give in to hatred and to protect their younger sister, Shirahoshi. Since then, his primary driving force has been to achieve his mother's dream of bringing Fish-Man Island to the surface to live under the real sun, fostering a peaceful coexistence between fish-men, mermaids, and humans. He seeks to break the cycle of inherited hatred that plagues his society, a goal that requires him to confront the dark history his family had long ignored.

In the story's narrative, Fukaboshi plays a central role during the Fish-Man Island conflict. He initially searches for the Straw Hat Pirates to deliver a message from Jinbe but becomes suspicious of them due to a worrying prophecy from Madam Sharly. When the New Fish-Man Pirates, led by Hody Jones, stage a coup and capture his father, King Neptune, Fukaboshi and his brothers charge to the rescue. They prove their strength by defeating waves of enemies, but are ultimately overpowered and captured after Hody's officers consume Energy Steroids. After being freed by Luffy, he provides crucial support in the final battle. He carries Luffy through the ocean, where the Devil Fruit user cannot fight, and aids in the effort to stop the destruction of the ancient ark Noah. Following the victory, he represents the royal family in the quest for a new future, later accompanying his father and sister to the World Summit in Mary Geoise.

Key relationships are the foundation of Fukaboshi's character. He is fiercely loyal and protective of his family, particularly his younger sister Shirahoshi, whom he and his brothers vowed to guard with their strength. His father, King Neptune, is a figure of authority and past strength, while his younger twin brothers, Ryuboshi and Manboshi, are his constant allies in battle, with the three being known as the three strongest warriors of the Neptune Army. His relationship with his mother is the most defining; he carries her torch of peace and works tirelessly to collect signatures for her cause even years after her death. Regarding the Straw Hats, he evolves from suspicion to deep trust and gratitude, ultimately exposing his emotional vulnerability to Luffy and begging him to destroy the "ghosts of the past" endangering the island.

Throughout his development, Fukaboshi transitions from a prince who was perhaps naive about the deep-seated anger within Fish-Man Island to a true leader who confronts it directly. During the climax of the battle, he tearfully admits that the royal family had ignored the growing hatred in places like the Fish-Man District, allowing it to fester into a destructive force. He acknowledges that this cycle of hatred could lead to his nation's self-destruction, and he humbly asks for Luffy's help to reset everything to zero, showing significant growth in his understanding of leadership and peace.

As a fighter, Fukaboshi is exceptionally strong, possessing enough power to overwhelm giant sea beasts with ease. He is a master of Merman Combat and Merman Jujutsu, techniques that manipulate water to attack. His known techniques include Kouin Ryuusuisou, or "Time-Flowing Water Spear," a rapid slashing attack with his trident, and Ultramarine, a technique where he gathers a large volume of water to strike an opponent. His speed in the water is also highly renowned, earning him recognition as one of the fastest swimmers on the island.