It's April of my third and final year in high school... But the beautiful girl I have a crush on is my best friend's girlfriend. Thus begins my year of treading on the dangerous ground...

Ritsu, who has gotten somewhat chubby from eating her roommate Ruka's cooking, becomes determined to lose 7.5kg in three months. When Ritsu's attempt at a salad-only diet proves destructive, Ruka sets her on a new diet that allows her to eat delicious meals that are under 400kcal each.