Lulucy Lu is a central character who joins the protagonist Hiraku Machio in the Forest of Death, becoming the first official resident of his farm. Her background reveals a life of academic pursuit and subsequent danger; she is a scholar by nature, deeply interested in botany and the study of plants. This passion led her to create medicines for a group of nobles. However, instead of rewarding her work, the nobles attempted to steal her research results. In a desperate act of defiance and self-preservation, Lulucy destroyed their castle and fled, which left her severely weakened and on the run from their hired pursuers.

In terms of personality, Lulucy is bright, cheerful, and generally easygoing, often bringing a sense of wonder and enthusiasm to the simple life of farming. Despite her scholarly background, she has a playful and slightly messy side, sometimes acting childlike and failing to tidy up after herself. She is also known to enjoy drinking and is often one of the first to become intoxicated at village banquets. However, beneath this lighthearted exterior lies a sharp and capable mind. She is fiercely protective of her new home and family, and she is not afraid to use intimidation or threats to defend them, as demonstrated when she confronted the Demon King to ensure cooperation following an attack on the village children.

Her role in the story begins when Hiraku finds her in a vulnerable state in the forest, her clothes tattered and her energy spent. After she drinks a small amount of his blood to regain her strength, he invites her to live and work on his farm. This invitation leads to a humorous cultural misunderstanding, as Lulucy interprets his phrasing as a marriage proposal, a notion she excitedly accepts, cementing their close bond. As time passes, she becomes far more than just a farmhand. She evolves into Hiraku's most trusted confidante and advisor, acting as a de facto leader in the growing Big Tree Village. On multiple occasions, she manages affairs behind the scenes without Hiraku's direct knowledge, ensuring the smooth operation of their burgeoning community. Her role as the first lady of the village is solidified by her relationship with Hiraku, and she later becomes the mother of his child, Alfred.

Lulucy possesses several notable abilities that make her indispensable. As a vampire, she requires blood to maintain her strength and has the ability to alter her physical age and form to suit her needs. More importantly, she is a highly skilled and powerful magician. Her scholarly nature means she is well-versed in many fields and uses her magical talents to create convenient tools and items to assist with daily life. Her passion for botany directly aids in the farming efforts, and her extensive knowledge of magical theory leads her to establish a magic academy in the village to educate others. Over the course of the series, her character develops from a frightened fugitive seeking a hiding place into a confident, assertive, and deeply loyal matriarch who is integral to the village's prosperity and safety.