The Japanese name for Diancie and the Cocoon of Destruction is The Cocoon of Destruction and Diancie (Hakai no Mayu to Diancie)
For those who don't know, Meteor 淋浴 at Dawn is the song for Diancie and the Cocoon of Destruction (Pokémon the Movie 17). 你 can listen to it
link, but it's only in Japanese.
Of course Meteor 淋浴 at Dawn might not be the English name. Japanese 神奇宝贝 movie songs tend to be named after the first words in the song, and one of the first words is
yoake (dawn). But as many of us know English songs aren't usually like that.
Lyrics:
Yoake mae fukiareta kaze wa nanno maebure?
Uso de katameta HAATO hagare ochiteku
Nakanai to yakusoku shita no ni tomaranai SUKOORU
Kimi no koe ga fui ni kikoeta...
