Suika hails from Ishigami Village, founded by descendants of astronauts who survived Earth's petrification while aboard the International Space Station. Suffering severe nearsightedness, known locally as "blurry sickness," she improved her vision using a helmet carved from a hollowed watermelon, leveraging the pinhole effect. This unique headgear caused facial grimaces and an unusual appearance, leading to social ostracization. Her life shifted upon meeting Senku Ishigami, who accepted her helmet without question and later crafted corrective glass lenses fitted within the melon rind, restoring her sight. This act forged deep loyalty, making her one of Senku's first allies and a devoted member of the Kingdom of Science.

Initially a scout, Suika demonstrated exceptional stealth by rolling inside her melon helmet to infiltrate enemy territory undetected. Her reconnaissance proved vital, gathering intelligence on villagers' needs for Senku's strategic bribes and smuggling a concealed blade to Gen Asagiri to sabotage Hyoga's spear during the Stone Wars. She displayed bravery as a decoy, deliberately leading Tsukasa Empire soldiers away from Ishigami Village to protect others. Her unmatched survival instincts and knowledge of local flora and fauna, recognized by Francois, enabled her to identify medicinal plants and safely navigate hazards like volcanic gas fields.

After a petrification attack struck the Perseus, Suika and Ginro remained unaffected. She created a distraction by breaking glass to evade Ibara's forces, located the critical mobile laboratory for revival fluid production, and helped smuggle it off the ship under Senku's direction—crucial for the Kingdom of Science's recovery. Later, stranded alone in South America when the crew petrified, Suika survived for years in the Brazilian wilderness, foraging for food, constructing shelters and boats, crafting clothing and tools, and persistently recreating the revival fluid despite repeated failures. Her eventual success revived Senku, marking her evolution from scout to capable scientist. During this isolation, she physically matured into a taller adolescent with longer hair styled in stem-like strands, wearing weathered, self-repaired versions of her signature poncho and shoes.

Suika blends curiosity, kindness, and resilience. She readily volunteers for tasks, forms quick friendships like with Mirai Shishio, and shows compassion even to adversaries, saving Charlotte from a venomous spider bite. Her analytical skills let her deduce Kinro's nearsightedness mid-combat and interpret cryptic clues like Gen's floral trail. Though initially fearful during perilous missions, she perseveres to contribute meaningfully. Post-timeskip, her demeanor reflects increased confidence and determination, honed through solitary survival and scientific experimentation. Her abilities expanded to include crafting, amateur tailoring, and applying Senku's medical knowledge, alongside foundational stealth and environmental navigation. The breaking of her melon helmet in battle ended her signature rolling technique, underscoring her growth beyond reliance on it.

As a symbol of trust and friendship, Suika used her own blood to inscribe Einstein's mass-energy equivalence formula (E=MC²) onto her poncho after reviving Senku in South America, mirroring the equation on his tunic. This act reinforced her role as both a legacy bearer and an emerging innovator within the Kingdom of Science's mission.