you found..
mega sachiko EX was a promo given to attendees of the countdown for the 20th anniversary of the poke tcg in minato, tokyo, october 2016. the bulbapedia page linked with the card will have more info about that, what amuses me about the card is the attack, galaxy voice, for 4 fairy energies, does 10 damage times the seconds you can continuously sing "Ah♪", making it an easy contender for the hatsune miku theme deck. personally i could only go for at most 21 seconds, making the attack decently viable in the expanded format. unfortunately the energy cost for the attack is too high and with no fairy energy accelleration (as far as i'm aware), it would be a pretty difficult hit to set up. the fact that it's a mega and there's no sachiko spirit link to bypass the mega pokemon's turn end on evo downside makes it pretty rough to play, that and also there's no sachiko EX to actually evolve from, unfortunately making this card unplayable. i tried :(
here cheese