Fukaboshi

First Prince of the Ryugu Kingdom. Eldest of the three Neptune brothers. A shark merman.

Born in Fish-Man Island. 24 years old. Birthday is February 4th. Height 604 cm. Aquarius. Blood type S. Favorite food is abalone steak.

Possesses enough strength to overwhelm giant sea beasts, and together with his younger brothers Ryuboshi and Manboshi, they are called the "Three Strong of the Neptune Army." His weapon is a trident. His special technique is the merman jujutsu "Kouin Ryuusuisou (Time-Flowing Water Spear)." He can also use "Ultramarine" merman jujutsu. He is sincere and loyal, and he is highly trusted by his people. Although not as much as his father or sister, he has a huge body, more than twice the size of Luffy. Luffy calls him "Brother Hoshi."

10 years ago, he swore with his brothers to their mother, Queen Otohime, to become fine warriors and protect their sister. Since then, he has carried on his late mother's wishes, gathering many signatures over 10 years.

During the Fish-Man Island arc, he visits Mermaid Cove to invite the Straw Hat crew to the castle, but due to a misunderstanding caused by the mermaids hiding the crew, they miss each other. When the Straw Hat crew occupies the Ryugu Palace, he delivers a message from Jinbe to Zoro. In the town with the waterwheel, he captures Dosun, who was forcing people to step on a picture of Otohime. He heads to Gyoncorde Plaza with his brothers to rescue their captured father, Neptune, from the New Fish-Man Pirates, but they are defeated by officers who have taken Energy Steroids and are captured. Later, they are freed by Luffy and his crew, and the three brothers support Luffy in defeating Hody and preventing the ark "Noah" from falling.

In the Reverie arc, he visits Mary Geoise with his father and siblings. He senses an unpleasant aura on the "Travelator," the walkway leading to Pangea Castle.