Cofun Gal no Coffy follows Tumulus Gal Coffy as she enrolls at Tumulus High School, a place where a barrow tomb from the Yayoi period, the royal successor of the tumulus world, an American grave, a Sengoku‑period commander who serves as a teacher, and various other tumuli gather together. The story celebrates tumulus‑themed romance, friendship, and youthful adventures in a cemetery‑school comedy.