Hajime Ichinose's ordinary life is in for a change when a transcendent being named J.J Robinson hands her a small book called NOTE—a device which transforms her into one of the Gatchaman, the legendary protectors of Tachikawa City. Stressing that the existence of their group must remain a secret, fellow Gatchaman Sugane Tachibana takes Hajime to their base of operations, where Paiman, the panda-like alien leader of the Gatchaman, reveals their purpose: to eliminate aliens that pose a danger to humanity. These existential threats, called MESS, are becoming increasingly dangerous, destroying everything they touch. Now it's up to the Gatchaman and their new recruit to stop them before the world is engulfed in chaos.

Shinobu Oomiya once left Japan to participate in a homestay in England. During her time there, she became close friends with Alice Cartelet, the daughter of the family she was living with. However, when it was time for Shinobu to return to Japan, the two were able to express their sorrow despite the language barrier between them. Five years later, now a first year student in high school, Shinobu receives a letter by air mail in a language she does not understand. This letter is penned by none other than Alice, detailing her own homestay in Japan. In fact, Alice will be attending Shinobu's high school and living with her! Alongside their friends Youko Inokuma, Aya Komichi, and Karen Kujou, the five girls attend school together and learn about what their different cultures have to offer, day after day.

After Germania invaded a neighboring country in 1939, Europe spiraled into a devastating war. During the war, Germania set its sights on the weak alpine country of Elystadt. Boasting a far superior military and having achieved profuse success earlier in the war, it was expected that Germania would conquer Elystadt with ease. Matters are only made worse for the small country when Germanian soldiers capture their princess, Ortfiné Finé Fredericka von Eylstadt, as she is heading to a crucial meeting with Britannia. Yet, when a concurrent Germanian transport mission goes awry, Izetta, the last witch alive, escapes. When she recognizes Princess Finé from her childhood, Izetta rescues her from the Germanian soldiers by making use of her magical abilities. Now reunited with the princess, Izetta pledges to protect Elystadt from Germania, and with the last surviving witch on their arsenal, Elystadt hopes to turn the tides against the imperialist war giant.

Shinichi Chiaki is quickly making a name for himself as the principal conductor of the revitalized Roux-Marlet Orchestra, and Megumi Nodame Noda has made leaps and bounds as a pianist at the Conservatoire de Paris. However, tensions mount between the two as Nodame feels left behind by Chiaki's growing success and his close friendship with legendary piano prodigy Rui Son. Disregarding her teacher Professor Charles Auclair's advice, Nodame enters another piano competition in an attempt to jumpstart her own performance career. Meanwhile, those around Chiaki and Nodame are at their own crossroads. Rui begins to doubt herself after hearing Nodame's playing and being denied tutelage from Auclair; Maestro Franz von Stresemann faces the reality of his mortality; pianists Yunlong Li and Tatiana Vishneva feverishly prepare for a competition, while the latter also struggles with her growing feelings for oboist and fellow student Yasunori Kuroki. As Chiaki, Nodame, and their friends continue on their respective journeys, they must not only strive to stay true to themselves, but also remember where it all started.