Katsura and Midori are in their third year of high school and are about to graduate. During these three years of high school, Katsura has made many friends and playmates, but Midori has only Katsura. With each passing day, Katsura becomes more and more active with men and becomes absorbed in social media, living a vibrant life in a world Midori knows nothing about. Knowing this, Midori suddenly stops going to school, wanting Katsura's attention and concern. Katsura's loneliness doubles with Midori gone, and in an attempt to fill the void, she becomes increasingly absorbed in playing and escaping reality. The one who supports Katsura's emotionally unstable life is a mysterious person she meets online who claims to be a high school teacher named Kinmokusei.

"I loved you the most, but I knew the least about you in the world."