Shun is a transfer student who can't seem to adjust to his new class and falls into mild depression. However, one day he meets some fellow students by chance in front of a creepy Western-style mansion called the "Jailhouse" which is rumored to be home to a hideous blue monster. Soon, the group of six students, led by Shun and Anna, become trapped inside and desperately attempt to escape before the monster finds them.
Through a coincidence Tozaki runs into Kurata, his first crush from high school. They begin a relationship, but Kurata's jealousy starts causing problems.
The love of four high school students who get involved in a complicated way. A sweet and painful school love story.
