Bullied girl is in a coma after hanging herself due to the cruel ridicule and physical antics (pouring water on her and locking her in the bathroom stall, holding her down and messing with her hair, and heckling) of the rotten kids in her grade in high school. Although in a coma, she appears in her own room, at her computer, with a class picture with all the students. A specific curse, through the use of a cell phone that forewarns those sent it (a tune and "death message" arrive to those intended to possibly die), will be visited upon those who tormented this girl as we watch as they try to survive, either by forwarding the message (there is a "way out" that if you forward it to someone else you are freed from the curse) or making damn sure those with the message don't get the chance to send it to somebody else.
That good ole mainstay--through the use of the supernatural, those who were cruel to somebody get it right back at them something worse--of bullying is always ripe for use in seeing victims get what's coming to them in the horror genre. Right at the beginning, the victimized girl, Asuka, earns our sympathy. Only Emiri, her best friend at one point before she decided (much to her regret) not to help out Asuka in all the horrible bullying, and Emiri's sweet deaf boyfriend, Jin-wo, really are the least bit worthy of any emotional investment in regards to the threat of the curse. Ultimately, the curse of Mimiko, a little girl who died of asthma, ends up explaining why Asuka is (or really isn't) able to inflict harm towards her tormentors. The low budget is quite obvious in the tacky (but charmingly amusing) death sequences (the power line electrical cord strangling is my favorite; but the choking and spitting out of chicken feathers is quite a laugher). Seeing the students doing whatever they can to save their own skin (one kid is rushed into a closet by other students who guard the door because he got the message, not letting him out as the ghoul breaks his fingers and eventually destroys him), and proving that friendship is the least of their concerns when it comes to survival, tells you all you need to know about how much they deserve to be mistreated.
Obviously vigilantism is exposed here (no matter what you are put through, if you resort to the same behavior as those who tormented you, are you any better than them?), but horror film has a way of being cathartic for those of us who have endured the horrors of bullying. The red candy ball pops out of the mouth of victims as a kind of visual gag that is like a calling card for the ghost killer. The cell phone, how significant its use is for people, is as good a plot device in the spread of the curse as anything in horror in our modern age. The "let's stop the curse by a power of positivity" message being sent to Asuka's computer by a large number of people in the South Korean city where the students are touring and in Japan is a bit hard to swallow, and seeing Asuka's computer (and Mimiko herself being hurt by the chain message) "react" to it is a bit hokey. Still if you like these movies where the ghost girl emerges, this might be a fun diversion. I admit, it was for me.