The story is set in an alternate world called Yamauchi, ruled by the Yatagarasu clan, who are able to transform between human and crow forms. Yukiya, a beautiful and eccentric Yatagarasu boy, is chosen to serve the young prince. While encountering various events in the conspiracy-filled imperial court, he forms a strange master-servant relationship with the young prince.

"Let's help each other and aim to become perfect ordinary citizens." Kobato, who once had a bitter experience through deduction activities known as "wisdom work," was determined to become an honest and humble citizen. He secretly formed a reciprocal relationship with his classmate, Osanai, who shared the same aspiration, planning to make their high school debut as ordinary citizens and lead peaceful days. However, for some reason, mysterious incidents and misfortunes keep coming one after another into their school lives. Will Kobato and Osanai be able to achieve peaceful days as ordinary citizens?

Kazuhiko Nukumizu, a self-proclaimed "background character," accidentally witnessed his popular classmate Anna Yanami being rejected by her childhood friend. Since then, Kazuhiko has become involved with several loser heroines, including Anna.

Fable, an assassin who works in organized crime, has been raised to the legendary status of a ruthless killer capable of murdering any man within six seconds. Six years after his debut, his boss fears that Fable has started to attract too much attention from the legal authorities, and he orders him to hide in Osaka for a year. Accompanied by his driver who assumes the identity of his sister, Fable is bound by a special condition: he must act as a civilian and not murder anyone lest he and his partner lose their lives. However, the seemingly well-deserved holiday soon takes a grim turn. Takeshi Ebihara, the second-in-command of the Osaka mafia that officially protects the assassin, sees Fable's presence as a threat and wants to remove him. Constantly monitored by the yakuza and regularly put in life-or-death situations, Fable has no other choice but to outwit Takeshi's schemes if he wants to stay alive.