This is an overlong, melodramatic supernatural Vietnamese horror movie on the perils of fame and fortune. The Guardian centers on creepy dolls and the aspiring pop stars who make wishes and present sacrifices to them, and at over two hours long, still manages to squeeze in scenes of pop music performances with dance sequences, a love affair, and some other side stories that would've been better off on the cutting room floor. There's a high quality to the direction, cinematography, acting, and overall style, but none of this can compensate for a padded story, and a shopworn "creepy doll horror movie" story at that. The plot twist/big reveal isn't bad, but it comes across as forced as the movie's overall messages about success in the music industry being not all it's cracked up to be.
Indeed, the movie's comments on said fame and fortune grow increasingly tiresome. 1980s afterschool specials about Satanism and/or underage beer drinking are less heavy-handed than this, and, to their credit, '80s afterschool specials didn't resort to creepy dolls and ugly sacrifices of baby birds to make their points. There's a feeling throughout The Guardian that it should be better than it is. With a bit more editing, it might have been a decent supernatural horror story rather than a weird melodrama with creepy images and suicides. That said, if the movie's purpose is to make those younger viewers who are considering a career in pop stardom to maybe find another line of work on LinkedIn, it's successful enough in that regard, but as an attempt at a supernatural horror story, it falls short.