Ayumu faces the common high school problems of grades, fighting with friends, and a general feeling of isolation, but she deals with them by compulsively cutting herself.
See Also: すえのぶけいこ Keiko Suenobu is a female Japanese shōjo manga artist from Kitakyūshū, Fukuoka. In 2006, Suenobu's manga series, Life won the Kodansha Manga Award for best shōjo manga. Wikipedia
Manami's actions are far beyond mere "pranks"; this manga portrays a cruelty and violence in everyday settings that is disturbingly unbelievable. It's been hard for me to decide, as the cruelty escalates, whether this is gratuitous or an attempt to show what happens when varying degrees of torture, indifference, and selfish pride go unchecked. On a similar note, it's been hard for me to distinguish whether my uncertainty stems from the manga being extremely effective--shocking and tragic--or whether the manga is simply bad.
These can be read quickly, partly because the words to pictures ratio is low and partly because the story drags the reader along. There may even be a light at the end of the long tunnel but I'm not buying volumes 10 through 20 to find out.