Takatoshi Minamiyama (Sota Fukushi) majors in art at an university in Kyoto. On the train to the school, he sees Emi Fukuju (Nana Komatsu) and falls in love with her at first sight. Gathering up all his courage, he speaks to her. They begin to date and enjoy happy days together, but Emi reveals her secret to him.

An environmental analyst is asked by the police to determine if two deaths by hydrogen sulfide poisoning are an accident - or a murder. But when he meets a young woman at both sites, a scientific mystery begins.

In the dawn of the Meiji period, the Gokumonjou, an inescapable prison, has been established in the middle of an enormous lake to counter the soaring crime rates the new era has brought. Serving as the ferrymen are the famous Kumou brothers: the eccentric family head, Tenka; the reckless but noble second son, Soramaru; and the guileless youngest, Chuutarou. In spite of their grim work, the three lead relatively peaceful lives in the ever-cloudy town of Oumi, together with their housekeeper, Shirasu Kinjou. But buried in the long history of Oumi is the legend of the terrifying "Orochi," a serpentine beast that awakens every three hundred years in a human vessel. Unbeknownst to Soramaru and Chuutarou, the actual job of the Kumou family is to seal the Orochi away before it fully revives—or the world will be plunged into destruction. Amid the monster's next resurrection, the Kumou family must find the resolve to keep laughing under the clouds.

Iku (Nana Eikura) joined the Library Defense Force after a member from that team retrieved an important book that was targeted for censorship. She is assigned to work under Atsushi’s (Junichi Okada) team. She endures Atsushi's harsh treatment and looks for the member who retrieved her book. She also finds herself becoming attracted to Atsushi. Iku meets female high school student Marie (Tao Tsuchiya) at the library. Maries has a hearing disability. She is also a childhood friend of Mikihisa (Kei Tanaka). Iku senses Marie’s strong feelings for Mikihisa. Asako (Chiaki Kuriyama) works as a clerk for the Library Task Force. She has frequent meetings with curator Shuji (Aoi Nakamura). This creates complicated feelings for Hikaru (Sota Fukushi). One day, Mikihisa is arrested because of a book he recommended to Marie. Official reason given is because the book is unsuitable for disabled people. The members of the Library Task Force are angered by Mikihisa's arrest.

Satoru is a young man with a warm heart. He has a cat named Nana, but, due to circumstances, he can't raise cat Nana anymore. He travels with Nana to find a person who will take care of Nana. During his travels, he meets various people like his childhood friend and his first love. His unknown past and secret are revealed.

Mei Tachibana is a high school student. Due to a traumatic incident when she was a kid, Mei has been unable to make friends or have boyfriends. By mistake, Mei then injures the most popular male student named Yamato Kurosawa. Somehow, Yamato Kurosawa likes Mei Tachibana and tells everyone unilaterally that Mei is his friend. One day, Yamato Kurosawa saves Mei Tachibana from a stalker by kissing her. From that kiss, their love story begins.