The series is centered on 27-year-old homeroom teacher Mika Suzuki (who only looks about half her age) and the eccentric and colorful students of her class.

Each of the six BD/DVDs will include one short. They will feature the characters in a "slighly risqué" light not seen in the main story.

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.