Sumaho-chan, nicknamed by Shinnosuke Nohara for her ever-present smartphone ("Sumaho-chan" meaning "Smartphone Girl"), is a Mexican teenager living in the fictional town of Madakueruyobaka. She constantly cradles her phone while walking and fiercely refuses to let others touch it. Her real name is Francisca, information she initially keeps from Shinnosuke.

Francisca exhibits typical adolescent traits: blunt, shy, and moody. Upon first meeting Shinnosuke, she snaps dismissively, "Don't touch my phone, you potato-head," when he tries to interact. When carnivorous cacti invade Madakueruyobaka, Francisca survives alongside the Nohara family and other townspeople. She joins their makeshift resistance, the Madakueruyobaka Defense Group.

As part of the group's plan to defeat the giant Queen Cactus by drenching it with water from the town supply, Francisca plays a key role: she operates the tap to release water into a large balloon. This crucial action aids the strategy to weaken the plant creature, marking her shift from an aloof individual to an active participant in the community's fight for survival.

Following the neutralization of the cactus threat, Francisca remains in Madakueruyobaka as peace is restored to the town.