The Little Progenitor from the Stars

No System, no rebirth, hard sci-fi, a strong female lead~1V1, both leads are each other's first and only, strong woman and strong man! The romance is a slow burn!! Plot comes first, romance second! The silly blurb Some Professor: Who are you? Little Fairy: I'm your ancestor! Some Professor: Are you a pig? How can you eat so much? Little Fairy: I'm your ancestor! Some Professor: Want to spar? Little Fairy: Your ancestor doesn't want to pick on someone younger! Some Professor: ... The proper blurb Jian Siyou, a little fairy from the M31 planet, spends her days eating, drinking, and having fun on Earth, never expecting to get caught up in a world-shaking conspiracy...