Luna, a renowned beast-taming genius, experiences an unexpected setback when she unintentionally forges a contract not with her infant Vermilion Bird, but with a flea. Despite the rarity of a celestial anomaly linked to royal Vermilion Bird blood, Luna cannot sense its power because the contract binds her to a low-tier creature at the bottom of the food chain. This accident forces her to give the flea her Primordial Blood, sealing their bond for life. Authorities warn that this misstep might ruin Luna's future as a beastmaster, leaving her standing at a crucial crossroads.