Fukaboshi

Fukaboshi stands as a colossal, powerfully built shark merman with a broad chest and thick arms. His face is long and narrow, ending in a sharp nose, with a small mark set at the center of his forehead and wavy pale blue hair spilling to his shoulders. Striped markings along his huge neck may be gills, and his tail is deep blue speckled with lighter dots. A dark wrap circles his waist over a very long sash, and a pale blue band loops across his shoulders and trails behind him as if afloat, a flourish his brothers, mother, and sister all share, hinting at a royal emblem or simply common family taste. He keeps a golden trident at hand. As a youth he looked nearly identical, though his features were softer and less stern, and he donned a light shirt for the Levely gathering at Red Port.

A deep sense of duty defines Fukaboshi. He personally searched for the trespassing crew rather than send guards, wanting to deliver Jinbe's message himself, and he stayed measured and courteous throughout, even apologizing to the mermaids he disturbed and sparing them once he learned they sheltered the Straw Hats. Calm and shrewd, he handled the palace standoff without losing his temper and struck a fair bargain with Zoro. His fury, when it comes, turns brutal, as Dosun discovered after forcing citizens to trample Otohime's portrait. Like his mother, Fukaboshi champions coexistence with humans, and after her murder he resolved to keep her ideals alive, confronting Hody to stop hatred from spreading. He grew philosophical about grudges, calling them illusions of the living, and admitted shame that even he once harbored quiet resentment toward humans, even as he ranks among the most accepting merfolk shown. Perceptive and thoughtful, he sensed early that Luffy was no true threat and later apologized for ever doubting him.

As children, Fukaboshi and his brothers Ryuboshi and Manboshi watched over their sister Shirahoshi while their mother Otohime preached across the island. When a World Noble crashed ashore and threatened Otohime, a frightened Shirahoshi unknowingly summoned Sea Kings, and Otohime departed with the noble to the surface for a week before returning safely and finally winning the citizens' signatures. Otohime then charged her three sons to grow strong and shield Shirahoshi, whose Sea King power she warned was dangerous. Soon after, Hody Jones assassinated Otohime amid a fire at Gyoncorde Plaza. At her side, the brothers heard her final wish not to hate on her behalf, and Fukaboshi swore to carry her work forward, giving a broadcast speech at her funeral vowing to fulfill her dream.

When the Straw Hats reached Fish-Man Island, Fukaboshi sought them at Mermaid Cove to pass along Jinbe's words, then grew wary after Madam Shyarly foretold Luffy destroying the island. Even after the pirates seized Ryugu Palace in self-defense, he showed no hostility, negotiated with Zoro through a Den Den Mushi, and kept his promise to deliver the message. During the New Fish-Man Pirates' uprising, he and his brothers, counted among the three strongest in the Neptune Army, cut down the giant sea beasts and pressed the enemy officers, who only prevailed by downing Energy Steroids. The princes were captured and chained for execution beside their father until the Straw Hats rescued them. Fukaboshi later saved Luffy underwater, apologized for his doubts, and the two became allies, with Luffy dubbing him "Brotherhoshi." Confronting Hody at last, he used his Merman Combat skill, manipulating water and unleashing Ultramarine, and learned the man was a hollow being shaped by borrowed hatred. He tearfully begged Luffy to end the cycle and return the island to zero. After Hody fell and the Sea Kings halted the sinking Noah, the royals and Straw Hats feasted in celebration, and Fukaboshi, who lost a drinking contest to Nami, told a withered Hody he bore him no hatred and asked only for his silence before the children.

As Levely approached, Fukaboshi convinced Shirahoshi to accompany the family to the surface. At Mary Geoise his uneasy instincts about the travelators proved sound, and when Charlos twice attempted to enslave Shirahoshi, Fukaboshi and his brothers moved to intervene, restrained by Mjosgard since they were royalty and could endanger their kingdom, while pirates like Sai and Leo dealt with the noble instead. Trident in hand and trained in Merman Combat like his father, the eldest prince remains next in line for the Ryugu crown.