Natalie Sr. was a guild receptionist for sometime at the Adventurer's Guild in Flatta. Upon Azusa's arrival in the Adventurer's Guild, Natalie greets her and after estimating the amount of money she earned for the slime crystals she turned in, has her register in the guild. To her surprise, Natalie states that her Immortality Ability is impressive. (Source: Slime Taoshite 300 Nen Fandom Wiki)