Ryuusui Nanami

Ryuusui Nanami comes from serious money. As heir to the Nanami Conglomerate, he grew up with every advantage, yet he is determined to prove that his success is earned through his own skill, not his family's fortune. When the Kingdom of Science needs someone to captain a ship and cross the ocean, Ryuusui takes the job, putting his lifelong love of sailing and model shipbuilding to real use as captain of the Perseus.

He is proud and a little self-indulgent, happy to show off his wealth and talent, but that same ambition makes him genuinely useful to Senkuu's group. He throws himself fully into the goal of rebuilding civilization, treating it as the ultimate challenge worth his effort. His confidence can come across as grating, and Minami, one of his companions, finds him more annoying than charming at times, though his skills usually win people over in the end.

Ryuusui's older brother, Sai, is part of the family business he left behind to join the adventure. Alongside Gen Asagiri and the rest of the Five Wise Generals, Ryuusui brings a different kind of resource to the team: not scientific knowledge, but the money, connections, and sailing skill needed to get the Kingdom of Science across the world.