From Tokyopop:
It's senior year, and Rica is seriously stressed out. She's got more homework, exams, and papers than she can handle, and was recently dumped by her boyfriend. In other words: Life sucks! One day, she's chatting online when she meets three classmates who hate school as much as she does. Together, they hatch a plan to blow up the school when no one is present. The countdown is on for X-Day ...

Featured in this manga is a side story called The Last Supper.