Lumachina Weselia holds the position of High Priest within the Church of Divine Beings. Raised with the conviction that revealing her body is reserved solely for her future marriage partner or the divine being "Kami-sama" (who she believes has watched over her since birth), her strong moral code drove her to investigate deep-seated corruption, embezzlement, and injustices plaguing the Church. This investigation prompted Cardinal Vishos to order her assassination. Paladin Gewalt was tasked with eliminating her, employing summoned monsters to exploit her vulnerability, humiliate her, and attack her during her escape.

Lumachina possesses transparent platinum blonde hair, hazel eyes, and notably smooth skin. Her physique blends mature beauty with innocent charm. Her typical attire is a red-and-white silk robe dress paired with high heels and a hat displaying her faith's symbol; the robe features strategic gaps revealing glimpses of skin while extending down to her knees.

Her personality intertwines deep religious devotion, profound naivety, and an unyielding commitment to justice. She firmly believes prayer summons divine aid, exemplified when she prayed during Gewalt's assault and interpreted Diablo's coincidental arrival as Kami-sama answering her plea. Her innocence extends to cultural beliefs, such as insisting marriage is obligatory if a non-divine being sees her naked. Despite facing lethal opposition from the Church hierarchy, she persists in exposing corruption, prioritizing morality over self-preservation.

Her story begins while fleeing through a forest with Paladin Tria. Tria sacrifices herself to a Trap Worm summoned by Gewalt. As Gewalt mocks her and attacks with a Beast Mushroom, Lumachina prays desperately. Diablo coincidentally crashes nearby during a magic test, crushing the monster. Witnessing his arrival during her prayer, Lumachina initially identifies him as God. After Diablo rescues her and defeats Gewalt, she accompanies his group to Zircon Tower seeking aid from Paladin Batutta, whom she trusts remains uncorrupted. During this journey, she contracts a curse requiring a dungeon expedition for a cure.

Her interactions with Diablo's companions are complex. She abandons the belief that Diablo is divine but develops deep respect for him as an adventurer. She immediately clashes with the Demon Lord Krebskulm (Klem) due to their opposing holy and demonic auras, creating tension requiring Diablo's intervention. Similarly, the Fallen Edelgard initially attempts to attack Lumachina, necessitating restraint.

Lumachina wields immense magical power, visualized as a pillar of light and exceeding Diablo's reserves. However, her abilities activate only during prayer, scripture recitation, or extreme distress. Her miracles focus on healing and recovery, including: 《Cure Light》 for wounds; 《Purification》 and 《Dispel》 for curses; 《Holy Fresh》 to remove status effects; and 《Divine Protection of Light》 for damage reduction and offense enhancement. A significant limitation prevents her healing magic from affecting her own body, restricting her recovery to potions; this may function as a balance for her potent miracles.

Within the Church, her allies included Tria, who aided her escape. Gewalt ceased assassination attempts after Lumachina healed his mortal injuries, leading to his resignation from the Paladins. Her primary opposition is Cardinal Vishos, who sanctioned her elimination for investigating Church malfeasance.