After battle in first season battleship Amanohara was serious damaged and need to repair. It land on island where a Gogyou festival just begin. Umakai Shintaro and his five girls student who know as Raimu Unit begin enjoy a peace time in that island. But the enemy still follow them around. How Umakai Shintaro and his five girls student fight against the enemy. Still his five girls student begin try to draw his attention into them.

The age of the demons has begun. Dr Faust has foreseen this rise of evil. Unfortunately, he is near death and is unable to personally battle this upcoming threat. Faust entrusts a young boy, Shingo Yamada, to take the responsibility of ridding the Earth of this new evil presence. Faust finds a birthmark on Shingo's forehead that signifies that he is the chosen demon fighter. Faust summons from hell what may be humanity's only hope of surviving: a less than enthusiastic devil named Mephisto rises. After signing a pact in blood to save humankind, Shingo and Mephisto set out to battle the supernatural world.

Set in the near future in the Great Era of Detectives, chosen people are born with supernatural abilities known as Toys (トイズ, Toizu). Those who use these Toys for evil are responsible for a wave of crimes and necessitate employing Toy-using detectives to help solve them. In the Yokohama District, Opera Kobayashi runs a detective agency named Milky Holmes, made up of four budding young detectives, Sherlock Shellingford, Nero Yuzurizaki, Hercule Barton and Cordelia Glauca, who each wield their own unique toys and train to become detectives at Holmes Detective Academy. The video game casts players in the role of Kobayashi, who must utilise Milky Holmes' unique abilities to stop the Thieves' Empire, a band of thieves led by the mysterious Arséne. The second puts players in the role of another detective, Ellery Himeyuri. The Alternative TV specials also take place in this universe, in which Kobayashi and Milky Holmes are assisted by another Toy user, Lily Adler, in fighting against the Thieves' Empire whilst visiting London. In the first two anime television series, the four girls of Milky Holmes, Sherlock, Nero, Hercule and Cordelia, end up losing their Toys during an encounter with the Thieves' Empire. Taken away from their rich lifestyle and thrown into an attic, the girls must try and regain use of their Toys or else face expulsion from Holmes Detective Academy. Futari wa Milky Holmes, which takes place two years after the other series, follows two young girls, Alice and Kazumi, who, inspired by Milky Holmes, form their own detective unit, Feathers, and fight against a group of thieves known as the Color the Phantom. Tantei Kageki Milky Holmes TD sees Milky Holmes help an idol named Marine Amagi recover her Toys, the seven Elements, which have been stolen from her.

Hidden away on a remote mountaintop, the Kokoro Library struggles to attract many visitors. Nevertheless, it is the home of sisters Iina, Aruto, and Kokoro, who consider it their mission to keep the library running in their parents' stead. Kokoro has long dreamed of becoming a librarian at the library with the same name as her, and tries her best to keep up with her older sisters. Due to the lack of patrons, the girls mainly spend their time sipping tea, chatting, and reading. However, as the number of mysterious visitors progressively increases, Kokoro begins to learn about the strange history of Kokoro Library—a place where small miracles seem to blossom.