Kokone Morikawa has a strange napping disease that distracts her from reality, one that makes the world of her dreams and the real world near indistinguishable. In reality, she is an average high school student preparing for her university entrance exams; but in her dreams she is a magical princess of Heartland, a machine-driven future where the use of artificial intelligence is forbidden. Within the seemingly imaginary dreamland, Kokone discovers more about her family's past and the secret that her father, a talented mechanic, has tried to protect her from. However, as the events between two worlds intertwine, she must now protect the secret from villainous entities, both dream-like and terrifyingly real.

Following Natsuki Enomoto's confession rehearsals with Yuu Setoguchi, their younger siblings Kotarou and Hina struggle to confess their own love. Despite a disastrous first meeting in middle school with her upperclassman Koyuki Ayase, Hina’s heart is captured by his warm smile. Initially confused by these newfound feelings, Hina soon realizes that she has fallen in love for the very first time. Chasing after her brother Yuu and her crush Koyuki, Hina also enrolls in Sakuragaoka High School; but the threads of love are far-reaching, and they entangle Hina and her friends. Boisterous but sensitive, Hina hopes to confess her feelings to the tender-hearted Koyuki. Meanwhile, Kotarou, oblivious to his own feelings for her, is determined to always keep Hina smiling. Suki ni Naru Sono Shunkan wo.: Kokuhaku Jikkou linkai follows Hina, Kotarou, and Koyuki in high school. Their youthful love forges new relationships, but also threatens to break others.

On her way to school one day, Suzume Iwato stumbles upon Souta Munakata, a young man searching for abandoned areas. The high school girl directs Souta to a nearby ruin, but out of pure curiosity, she herself decides to head to the same destination. Once there, Suzume discovers an isolated door with a dreamlike universe lying beyond it—a place that she can see and feel, but not enter. A strange stone rests on the ground nearby, but it turns into a cat-like creature and scurries away when Suzume lifts it. Suddenly afraid, she heads back toward her school, not realizing that her act of leaving the door open will have consequences. With the "keystone" released, the evil within the other universe can now freely escape and wreak havoc throughout Japan. Intending to correct her dangerous mistake, Suzume joins Souta—whose true goal is to prevent evil from festering—in finding and locking all open doors before the country is destroyed.

Love is blooming at Sakuragaoka High School. Natsuki Enomoto has finally mustered the courage to confess to her childhood friend, Yuu Setoguchi. However, in the final moments of her confession, an embarrassed Natsuki passes it off as a "practice confession." Oblivious to her true feelings and struggling with his own, Yuu promises to support Natsuki in her quest for love. While Natsuki deals with her failed confession, fellow classmate Koyuki Ayase struggles with his own feelings for Natsuki. Despite his timidness, he is determined to win over her heart. Zutto Mae Kara Suki deshita.: Kokuhaku Jikkou Iinkai follows Natsuki as she dreams of one day ending her practices and genuinely confessing to Yuu. Meanwhile, close friends also find themselves entangled in their own webs of unrequited love and unspoken affections.