One Night, Runa Amatsu, a girl who dreams of becoming a fairy-tale writer, sees a great magic circle appearing in the easter sky.
Two spheres of light descended from it and then it immediately dispersed.
The next day Runa's twin sister, Rena, and her best friend Miyu Kokubugata convince her to install a pirate app called "Angel Maker".

"Would you like to Blow Up? Yes/No".

--"She has been cursed by a magic item. The young girl was cursed".--

[Translated from DLsite]