Ai Uozumi, known as Sazer-Pisces, is a central figure within the Water Tribe. By profession, she is a caring and friendly nurse who works at the same hospital as Akira Dentsuin, a fellow Sazer she quickly develops strong romantic feelings for after their first encounter. This initial crush marks the beginning of her deep emotional connection to Akira, who operates as Sazer-Remls.

Personality-wise, Ai is defined by a notably kind and compassionate nature. This extends to a remarkable degree of mercy, as she has been shown to feel sympathy even for those who have attempted to kidnap or harm her. Despite her gentle disposition, she is also serious and completely devoted to the responsibilities that come with being a Sazer. She holds the distinction of being the youngest member of the GranSazers, which adds a layer of earnestness to her commitment.

Her role in the story is triggered when she and her long-time friend Tappei are attacked, forcing her to awaken her powers to defend herself. It is during this critical moment that she is saved by Sazer-Remls, solidifying her place among the warriors. A significant part of her personal journey involves discovering that a man she has known for years is actually a relative. When this relative is kidnapped by the antagonist Logia, she pursues them and successfully secures his freedom. As Sazer-Pisces, she represents the water element and is a vital member of the Water Tribe, which is led by Makoto Sorimachi, also known as Sazer-Gorbion. She fights alongside her fellow tribesman, Tappei Mikami, who transforms into Sazer-Gans.

In terms of development, Ai matures from a nurse with a crush into a fully realized warrior dedicated to her mission. Her initial vulnerability is gradually balanced by her growing seriousness and resolve as she confronts the dangers posed by the Impactors and other enemies.

As Sazer-Pisces, the water warrior under the astrological sign of Pisces, she dons aqua-colored armor that is visually shaped after an orca or whale. Her transformation is facilitated by a device called the Knuckle Riser, which all GranSazers possess. When the sign of Pisces on her left hand glows, she sets the Knuckle Riser to Transformation Mode and says, Equip, to assume her armored form. Her primary weapon is a small gun known as the Aqua Blitz, from which she can unleash a powerful finishing blast called the Blink Shot. For aerial combat and transportation, she pilots the Aqua Driver, a dolphin-based vehicle also referred to as the Aqua-Triber. Furthermore, as a member of the Water Tribe, she shares ownership of the Leviathan, the tribe's colossal Chouseishin that they can summon and pilot together.