He first used the pseudonym Kir Bulychev in 1965, for his very first science fiction story, "A Girl Nothing Can Happen To". It was the first in what would become his most popular book series, "Alisa Selezneva", that eventually comprised more than 50 novellas and short stories. This children's science fiction series is centered around the titular heroine, a teenage girl from the future, who travels through space and time, solves mysteries, makes discoveries and saves endangered peoples and species. Bulychov kept writing "Alisa" for the rest of his life: the last book appeared in 2003, months before his death. There were four animated and three life-action adaptations of "Alisa" stories, as well as tie-in comics and video games.