Prince Toma is the young ruler of Togenkyo, a floating island that drifts into the story of the film. The island rests above a magical spring that turns anything it touches into a male, so daughters are never born among his people. Because of this, the only way for Togenkyo's inhabitants to find brides is to kidnap them from neighboring lands, and Toma leads such raids with the help of three animal-themed retainers, human-animal hybrids who act as his lieutenants.

In personality, Toma is a capricious and self-assured young monarch accustomed to having his wishes fulfilled. He treats the search for a bride as a form of entertainment, forcing the abducted women to take part in strange and playful contests designed to amuse him. His motivation is practical rather than malicious: he needs a wife because his island cannot produce female children, and he sees nothing improper in taking brides by force. Despite his casual attitude, he carries himself with the pride and authority of a ruler, and he expects the women brought before him to compete for his favor.

His role in the story is that of the main antagonist after the abduction occurs. He captures several of the principal female characters along with many other women and brings them to Togenkyo to compete for the position of his bride. Ranma infiltrates the competition disguised as a female contestant, both to rescue Akane and to gain access to the island's spring water, which transforms whatever it touches into a male and therefore offers a possible cure for Ranma's curse. The bride selection ultimately leads to a direct confrontation between Toma and Ranma, ending in a one-on-one sword duel.

In terms of key relationships, Toma is served loyally by his three animal retainers, whose design recalls the companions of the folk hero Momotaro. His connection to Akane is the most significant of the story, as he selects her as his chosen bride not because of the contest results but because she openly scolds him for his treatment of the captured girls; her defiance impresses him more than the compliance of the other contestants. His relationship with Ranma is that of rival and opponent, with the competition for Akane turning into a genuine martial clash.

As a fighter, Toma is a highly skilled swordsman whose combat style relies heavily on illusions created by his sword, though he remains a capable fighter even without them. He is fast enough to evade the Chestnuts Roasting Over an Open Fire Fist and is nearly equal to Ranma in speed and basic combat technique, which makes their duel a serious test of Ranma's abilities. His notable abilities therefore combine swordsmanship, illusion-craft, and physical speed, all supported by the authority he holds over his island and its inhabitants.

In terms of development, Toma changes little over the course of the film; he remains the ruler of Togenkyo from start to finish, and the story does not present a deep personal arc for him. However, his decision to choose Akane after her rebuke shows that he is responsive to directness and strength of character, and his willingness to face Ranma personally in combat reveals a degree of honor beneath his self-indulgent exterior. He stands as a confident, magically advantaged, and martial-minded young prince whose island's unusual condition has shaped both his circumstances and his conduct.