While on a class trip to Tokyo, four girls who are rooming together decide to celebrate their friend's 15th birthday. All of the normal, birthday-type things happened, with cupcakes and cards and balloons, but when one of the girls decides to be creative with it, she stumbles upon a charm that bonds you as friends forever. It sounded easy enough, repeat a phrase four times and rip the doll, and eternal friendship awaits... It SOUNDED simple, at least.
The majority characters are a group of students from Gossamer High School for Girls.
- Aspen Sinclair (15 years old) - The youngest of the group and by far the smartest. She is a new addition to the group, because she was recently moved up from being a freshman to a sophomore. Aspen is very quiet, and because of that, nobody knows how smart she really is. She is very much a follower and rarely speaks to the girls, only very short sentences in hushed tones. She wants to be louder and more assertive, but can't push herself enough. Typically, when making choices, she is correct, but refuses to tell anyone they are wrong.
- Brooklyn Maddox (17 years old) - The leader of the original four girls. She is the oldest and therefore believes she is the leading figure the group needs. Brooklyn grew up in a lifestyle where she got everything she asked for, and is very pushy and whiny and sometimes throws fits when things don't go her way. She tries not to, and means well, but old habits die hard.
- Tetra Chamberlain (16 years old) - Tetra is the most observant and down to earth member of the group. She is described by others as sweet and thoughtful, and on all outward appearances is normal. However, Tetra is very possessive, paranoid, and wrathful to certain people. Those people describe her as cruel, unforgiving, and harsh. She does not easily warm up to people and watches them for extended amounts of time before approaching them.
- Viola Anton (16 years old) - One of the original four girls who performed the charm in the hotel room. She is hard-headed and defiant, and always acting upon impulse. She has enormous potential to fix that, as she is very smart, but she dislikes being told what to do and how to do it. As smart as she is, though, she is not very observant and overlooks most small details and is unable to catch onto hints and decipher codes, which hinders her greatly in both school and trying to find ways to avoid or get out of unpleasant situations.
- Callum Nix (17 years old) - He is the only other living being occupying the same closed space as Tetra upon her arrival at Heavenly Host. Callum is a scrawny boy from the other school that took the trip to Japan with the girls' school. He did the charm with 6 other people, one he described to be already dead. Callum claims he did not kill him, purposefully, which makes Tetra a bit paranoid. As time goes on, however, Callum grows an affection for Tetra, and vows to stay with her until they find a way out. Or they die, whichever comes first.
- Maggie Sinclair (32 years old) - Aspen's mother. She had Aspen as a teenager and is very protective over her. She is heard briefly while on the phone with Aspen. Viola voiced concerns that Maggie had said she felt uneasy and had bad feelings about letting Aspen go on this trip, and her concerns become reality when the girls are flung into Heavenly Host.
- Bryson - Bryson is Brooklyn's boyfriend and he is seen briefly before the charm is performed. He came into the hotel room for a short time to drop off something of Brooklyn's and wish Samantha a happy birthday. Bryson was also invited to perform the charm but declined because of gender-separated hotel rooms and a curfew.
- Melanie Jansen (16 years old) - A friend of Callum's. When she sees him with Tetra, she runs up and hugs him, making Tetra assume that they are more than just friends. She gets jealous and first commands her not to hug him, and then Melanie's behavior makes Tetra angry, and Tetra ends up jumping onto Melanie and killing her after a heated argument and fistfight.