Winter was once the only season in the world-but such an existence was too lonely to bear, and so it created Spring to love. Before long, the earth wished for more time to rest in the cycle, and Summer and Autumn were born. The ones who carry the cycle are called the Agents of the Four Seasons. Hinagiku, the Agent of Spring, disappeared from this land ten years ago, taking the season of spring with her. Now, after incredible hardship, she has returned to restore the cycle to its proper state-and, as in the myth passed down since the dawn of time, she sends her love to Winter. (Source: Yen Press)

Miyu Suzuki is a high school girl whose cheerful outlook on life is tempered by her need to fit in. Coincidentally, beside her in the classroom sits Yuusuke Tani, a boy unconcerned with others' expectations. Their exchanges rarely extend beyond brief discourse, yet the polarity of their demeanors unexpectedly draws them to one another. As their mutual interest grows, the newfound feelings are no longer easy to ignore. Eventually, Suzuki voices what is inside her heart, forcing both of them to confront the unspoken affection between them. With each passing moment, their relationship evolves, and they gradually come to better understand themselves and the person who is their polar opposite.

The protagonists of the series are the three Kisugi sisters—Hitomi, Rui and Ai—who run a café called Cat's Eye. The sisters lead a double life as a trio of highly skilled art thieves, leaving cards with the name Cat's Eye at the scene of their crimes. They steal works of art that belonged to their long-missing father, Heinz who was a famous art collector during the Nazi regime, in the hopes of him contacting them. Toshio, the police officer investigating this case is the fiancé of Hitomi. He also swears to capture and bring down the Cat's Eye Gang.

In a future where children are few and regarded as Japan's most valuable assets, Christmas has become a mere legend of the past. For the students of Daikoku Welfare Academy—a boarding school where they are educated, protected, and monitored—the mythical Santa Claus is a forgotten character of fiction. For the adults, Santa Claus is a very real menace that needs to be neutralized by the Saint Nick Pursuit Unit in case he makes an appearance. Shiori Fuyumura, a student of Daikoku Welfare Academy, is determined to find her best friend, Ichie Ono, who has been declared dead after being missing for six months. One morning, Fuyumura summons her fellow class representative, Kazushige Sanda, only to attack the unknowing boy. She is convinced that Sanda is the descendant of the infamous Santa Claus—the only person who can make her wish of finding Ono come true—and is determined to force out his dormant true self by any means necessary.