Two years ago, Mitsuki Kouyama's friend, Eichi Sakurai, moved to America before she could confess her feelings to him. Though she cannot contact him, they made a promise to fulfill their respective dreams: Mitsuki wants to become a professional singer, and Eichi an astronomer. She hopes that one day her music will reach him across the world with a brilliance like that of the full moon. There is just one catch: Mitsuki suffers from throat cancer, which makes her voice quiet and singing strenuous. Her grandmother, who has a hatred of music, insists that Mitsuki undergo surgery to remove the cancer, but she refuses due to the risk of losing her voice. One day, two shinigami—Meroko Yui and Takuto Kira—appear to tell her that she only has one year left to live. This sudden revelation spurs Mitsuki into action, and she decides that with Meroko and Takuto's help, she will become a professional singer in the time she has left. Full Moon wo Sagashite follows the emotional story of Mitsuki and her shinigami friends as they discover what it means to sing—and ultimately, what it means to live.

In ancient times, some witches married their familiars, who had taken human form, giving birth to a lineage of ogres. One such ogre is Morihito Otogi, who while appearing completely human, still retains the inhuman strength of his bloodline. Nico Wakatsuki is a young witch and Morihito's childhood friend, but as part of her education, she had to go to the Witches' Holy Land to train and part ways with Morihito. Years later, just before Morihito's first year of high school, Nico returns home with one goal in mind: to claim him as her familiar. While most witches choose a cat or a bat, Nico has her heart set on Morihito in more ways than one. Although seemingly oblivious to her true feelings, Morihito and Nico end up living together under the same roof with both of Morihito's parents elsewhere. While reluctant at first, Morihito accepts his new role, determined to help Nico seamlessly fit back in with human society and protect her from fated disaster.

Loid Forger, an elite spy, is warned by his handler that he may potentially be reassigned from his ongoing mission, Operation Strix. To maintain his position, he must make significant progress toward the operation's objectives, which involves having his adoptive daughter Anya earn sufficient Stella Stars to become an Imperial Scholar at Eden Academy. After learning of a cooking contest that awards the winning student with a Stella Star, Loid researches the judge's preferred dessert to help increase Anya's odds. However, perfectly recreating the judge's favorite meremere requires more than just following a recipe. Thus, the Forgers embark on a vacation to the Frigis region to try an authentic meremere. Not all goes smoothly on the trip, as the Forger family ends up entwined in a sinister plot to reignite war between the countries of Ostania and Westalis.

The streets of Treasure Town are said to belong to The Cats. They know everything that goes on in the city, and no one can stir up trouble without going through them first. In reality, The Cats are a pair of orphan boys called Black and White, who aren’t afraid of anything or anyone. But their rule of the streets is challenged when the Yakuza come to town and start making changes. The wild Black and the carefree White have no one to rely on but themselves to get their Treasure Town back to the way it was. But their bond is tested as they quickly realize going back to how things were may no longer be an option.