MONSTA X may be brooding and serious on stage, but they're always full of smiles behind the scenes as we can see from the newest jacket photoshoot cuts! 

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The boys, who are gearing up for a comeback with 'The Clan Part. 1 - Lost', have revealed some bright, behind-the-scenes photos from the set of their red, moody teaser images, gifting us with such charming little smiles!

'The Clan Part. 1 - Lost' is set for release this coming May 18! Check out MONSTA X' album highlight teaser and MV teaser if you missed them!