I wrote about Anamanaguchi before on this website. Loved there music then; still love it now.
No idea how I didn’t see this video before. “Prom Night” is on their 2013 album Endless Fantasy. This video’s from 2011, which means that they’ve been tinkering with the song for 2 years before realization. The final product is much more polished, and it’s got those strange talkey-voice sounds. “Vocals” I think they’re called.