Once, there was a mythical pokémon named Meloetta. She had a voice like none other which could heal the hearts of people and pokémon, alike. She was very kind to the people who protected her and to the pokémon that assisted those people. Meloetta also had friends among other legendary pokémon, such as the youngest and newest member of the "Swords of Justice", or "Sacred Swordsmen" who was called Keldeo.

Meloetta was unaware of it, but Keldeo also had a crush on her. Although Keldeo did like Meloetta a lot, he never wasted his feelings by getting jealous of the many other male pokémon who became infatuated with his love interest simply upon meeting Meloetta, because he knew she was too focused on other things such as making her own guardians happy to care much about boys. All of this was true until a human male came into Meloetta's sight one day. That is where the story begins.