A new life begins for Kitahara Iori as he begins his college career near the ocean in Izu city, full of excitement for his new life. He will be moving into his Uncle's diving store "Grand Blue." There he finds the beautiful ocean, beautiful women, and men that love diving and alcohol. Will Iori be able to live his dream college life?

At Fumidzuki Academy, classes are separated by academic achievement. The smartest kids are in A Class, while the dumbest are in F Class. This chronicles the daily life of the students in F Class. Instead of grades, they have to worry about homosexual stalkers, crushes, ambiguous genders, and waging academic war on the upper classes!

The protagonist is a guy who is among the stupidest of the stupidest in the school. In this school your grades can, under the supervision of teachers, take a virtual form to do battle! However, if you leave an examination midway, you get zero marks. A bright and cute girl, Mizuki Himeji, had a high fever during her examination. Despite her potential to be the second highest scorer in the level, she obtained zero marks for having left due to her illness and is thus banished to the worst class, Class F.
Grades mean nearly everything. For Class A: They have a smart-looking teacher, a plasma TV as big as the entire wall as their blackboard, personal laptops, personal air-conditioners, refrigerators, adjustable seats and all kinds of different appliances. Within the refrigerator, there are all kinds of drinks and snacks. Their ceiling is made of glass, the wall lets them put up high-class drawings and plants.
As for Class F (the worst class): They have Japanese desks and seat paddings. Their blackboard is dirty and there's even no chalk! Someone complains the legs of his desk are broken, so the teacher asks, "Didn't we distribute some glue to stick wood together? Glue it back yourself later." Another one complains the wind is blowing in from the broken window. The teacher says, "I got it. I'll apply for plastic bags and super-glue to fix it later." There are spider webs everywhere, not a patch of the wall is clean. A unique moldy smell spreads across the entire room; it must be from the old tatamis used to tile the floor. Welcome to Class F.
The protagonist feels displeased at such an arrangement; he seeks help from his friends to try to make a change through invoking war! And they devise all kinds of plans to try to beat the famous Class A, scheming to get Class A's classroom and equipment if they win.