Bullet Butlers

Legend has it that the heavens and the earth were divided by the atmosphere, with the sky named "Bresigrand" and the earth named "Goltrock."
In the past, an age of swords and magic existed on Goltrock. Monsters roamed the fields boldly, and different races—humans, elves, dwarves—clashed with one another.
However, the Undead King, exiled from the heavens, led an army of zombies in an attempt to plunge the world into darkness. All races of Goltrock were annihilated, but eight chosen heroes defeated the Undead King. The gods bestowed great glory upon these eight heroes...
—And so, two thousand years later.
The Industrial Revolution erupted. Democracy rose, swords were replaced by guns, and magic merged with science. Monsters were protected as endangered species, while fairies, dwarves, goblins, and beastfolk who had assimilated into human culture long forgot their wild skills and grew accustomed to cities filled with reinforced concrete skyscrapers.
Ocelot City is the most racially diverse metropolis in the world. Among the eight heroes, Ingrid Fortenmeyer, a dragonkin capable of transforming into a dragon, was especially renowned. As the chosen descendant of the gods, the "Mystic One," Land Fortenmeyer, who lives in the modern era, is also widely known as a symbol of the city. The half-elf protagonist, Rick Arrowsmith, serves as the butler of Selma Fortenmeyer, Land's adopted daughter who holds the qualification to inherit the Mystic One legacy.
He wields the sentient magic spear Vale Hunter, always protecting his mistress from enemies, and at times reflects on her past. Due to a certain incident in the past, Selma became an incomplete dragonkin who can only transform into a dragon form except for her wings—a "Lacker" (transformation disability sufferer). Since then, Rick has gone to great lengths to care for her, who lives in despair. Even so, the peaceful days Selma spends with her friend Valeria Forster and Valeria's butler, Watarase Yuki, continue smoothly.
However, the Holy Council, which had long held a grudge against the Mystic One, assassinated Land.
Rick's, Selma's, and the small world they inhabited began to expand endlessly—.