Kirby's Cave Story 5: The Legend of VaneYu is the sequel to Kirby's Cave Story 4: Snowdrop's Adventure.
The Doctor (From Cave Story) is causing destruction on VaneYu's homeworld. VaneYu watches in horror as enemies take over. She decides to send a distress call to some heroes to come save her homeworld by writing a letter. She sends the letter off into space and straight to Planet Popstar.
Meanwhile, Kirby, Sue, Meowkie, Kitty, and Snowdrop are in Kirby's house sleeping. Each of their alarm clocks go off and the heroes do their morning routines. They head outside after they're done. Suddenly, a letter falls from the sky and Kirby catches it and reads it. The letter was from VaneYu, who is calling for help to save her home planet. The five heroes set off to save VaneYu's homeworld, not realizing they're going to be joined by Riolu, Sagwa, and Samus Aran.