Set a few months after the original series, Wataru is called into action once again!

A long time ago, Haruka Hoshinogawa made a wish with the town's old cherry blossom tree with her grandfather while receiving a present from him: a cherry blossom ribbon. As she grew up, she treasured the gift that was given to her while starting fifth grade in her school. One day, upon noting that the old cherry blossom tree is wilting, her grandfather decided to leave the shop to explore the world and let Haruka take care of the store in his absence. The next day while sleeping, her treasured ribbon sprouted a strange egg, revealing a Cocotama, a god born from an object that has been cherished with love and care. Haruka woke up and accidentally saw the Cocotama on the table, retreated to her Hiding Egg. As Haruka picked it up, it has changed into a mysterious key. Left with some questions, the Cocotama introduced herself as Ribbon, and Haruka learned about the existence of her kind and the mysteries behind the strange key she had. Ribbon realized that the key is actually the Key of Wonders and that Haruka was chosen by it to be the Legendary Contractor to the Cocotamas. Now, both of them try to run the shop and meet new Cocotama friends, while discovering the mysteries and powers behind the Key of Wonders.

Hiiragi Kashima and Shizusumi "Shizu" Yagi's band "syh" is set to debut, but they run into trouble when their support guitarist leaves. Although Hiiragi often clashes with Ritsuka Uenoyama—the smug boyfriend of his childhood friend Mafuyu Satou—Hiiragi convinces him to perform as their temporary member. Despite their friction, Hiiragi acknowledges Uenoyama's talent and respects his hard work—to the point of asking him to complete an old song that Mafuyu's ex-boyfriend, Yuki Yoshida, left behind. In between writing, recording, and filming a music video, Hiiragi comes to terms with his love for the aloof Shizu and wrestles with how to convey his feelings. Meanwhile, "given"—composed of Uenoyama, Mafuyu, and their bandmates Haruki Nakayama and Akihiko Kaji—receives an offer to debut as well. The members are ready and beyond excited, save for Mafuyu, who has never before thought about playing music professionally. As Uenoyama attempts to understand Yuki and replicate his unique sound, Mafuyu steps back to ponder over the looming changes in his life, fearing what the uncertain future may bring.

October 1941, as the second World War threatens to destroy the civilized world, an unforeseen complication suddenly occurs. An alien invasion! Despite the sudden appearance of these extraterrestrial aggressors, the Axis and Allies continue their destructive conflict. Only the Kishin Corps and their giant Geo-Armor Robots (a.k.a.: Kishin), developed from a captured alien robot soldier, stand between the Earth and total annihilation! A teenager, named Taishi, suddenly finds himself at the center of a struggle over a mysterious black attaché case entrusted to him by his father, Professor Tokamura. The case contains the controlling mechanism for one of the giant Geo-Armor Robots, and the Japanese Kanto Army, the alien invaders, and the Kishin Corps all want to recover the device! Between the spies, the armies, the aliens, and the Giant Robots, Taishi is in for an epic adventure—if he can survive it!