Usagi's family goes on vacation to a hot springs resort near the lake where Usagi's parents met. Queen Beryl notices that there is an unusual energy surrounding the lake and sends Endymion to investigate. He discovers that there is a monster buried... (more) underneath the lake and uses his powers to revive her. The monster soon starts attacking Usagi's family. Endymion accepts responsibility for unleashing the monster and protects the Tsukinos. When the other Sailor Warriors arrive, he helps them defeat the monster and release the girl's sou. Sadly, he flees again before Sailor Moon can talk to him.