X-Day (彼女たちのエクス・デイ Kanojo-tachi no X-Day?, lit. "X-Day of Her and the Others") is a two book manga written by Setona Mizushiro. It is about three high school students and a teacher, who meet online and form a plan to blow up their school.
Saginuma Rika, Shimada Nanaka, Tsukumura Yumihiko, and biology teacher Katano Reichi meet in a chatroom, where they go by the screennames 11, Polaris, Mr. Money, and Jangalian. While there, they discuss their frustrations with their school and form a plan to blow up their school, which they see as the source of all their problems. As the characters get to know each other, they begin to realize that their problems are situated in other aspects of life as well, not just from the school.
The characters find solace in each other; a major topic of the manga is loneliness. All of the characters implode inside as their problems condense. Jangalian is stalked by his boss's daughter, 11 can't deal with a younger girl's presumed superiority, Mr. Money has an abusive mother, and Polaris is crippled by shyness when she is not dressed as a gothic lolita. They deal with their problems through helping each other.
The Last Supper
"The Last Supper" (最後の夕食?) is a side story included in volume 2. It is a fable set in the far future, at a time when the sun and rain are man-made and cows have died out. Because of this, humans develop a being that consists of a cow's DNA, treating them in the exact way as they would a normal cow. The being is very similar to a human, only adopting ears and a humorous outfit consisting of a cow bell and long dress-like outfit in difference. In the fable, a boy named Mitsuhiko confronts a cow (Lamda) owned by his father's ranch and the story goes on from there. The story expands and relationships develop and it all becomes very heart-wrenching and sweet.
X-Day was written and illustrted by Setona Mizushiro and serialzied in the monthly shōjo manga magazine Princess in 2002 and 2003. The nine chapters were collected in two tankōbon volumes by Akita Shoten under the Princess Comics imprint. It is licenced by Tokyopop is in North America and Germany. In France the series is licensed by Asuka.