Elfriede the Exterminator

is a Japanese light novel series written by Akaneya Matsuri, with illustrations by Mamuru. The series began publication on December 10, 2013 by ASCII Media Works under their Dengeki Bunko publishing imprint.

Synopsis
Due to a catastrophe called the Sea Crater Incident, the area including the metropolitan area suddenly became the "sea" one day.

Minsuke Yoshioka, a second-year high school student who attends a warship school floating in the sea created by this disaster, will participate in the naval battle tournament and burial selection battle held at the school with his classmate Elfriede. ―.