Oh, and for anyone who doesn't know the groups but wants to check them out!
They all have a Weekly Idol episode together, and I'm serious, it might be the funniest and best episode ever xD.
https://www.youtube.com/watch?v=k4wjuANRCaM
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Astro - Breathless
They are super cute!
https://www.youtube.com/watch?v=aBNyHAasnSM
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KNK - Knock
Listen to these beautiful voices! I swoon so hard!
https://www.youtube.com/watch?v=HYVDIZcb6Og

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4Ten - Severely
https://www.youtube.com/watch?v=BxpOCMH3NeQ