Lisa Fukuyama is the younger sister of Kazuharu Fukuyama and a first-year student at Mizuno High School. She is a self-taught sorceress who specializes in black magic, having first used her abilities to bring a doll named Eli to life. Her magical experiments frequently spiral out of control, leading to chaotic incidents such as infesting the family mansion with ghosts, summoning a giant octopus in the school swimming pool, and causing an explosion in a shopping center. Despite her often reckless spellcasting, Lisa is extremely confident in her skills and dislikes being told she is wrong.

Her personality is marked by a strong sense of narcissism and competitiveness. She is accustomed to wealth and status and uses her family's resources to get what she wants. A key motivation for her actions is a fortune she heard on a radio program, which convinced her that Yukinari Sasaki is her destined soulmate. From that point, she relentlessly pursues him through magical charms, schemes, and even outright kidnapping, all much to the dismay of her brother Kazuharu. This puts her in direct rivalry with Miharu, whom she sees as an obstacle.

In the story, Lisa functions as a recurring comedic antagonist, frequently creating trouble for the main characters. She is supported by two loyal bodyguards, Hayate and Kosame, who follow her orders. Despite her jealousy of Miharu, she develops a fondness for Ebi, as the doll-like girl reminds her of Eli, the animated friend she lost when the magic on the doll wore off. Over the course of the series, Lisa demonstrates intelligence and resourcefulness in devising her plans, and on rare occasions shows a more caring side toward those close to her. However, her obsessive pursuit of Yukinari and her reckless use of magic remain defining traits throughout her appearances.