Two souls, living very different lives, wander alone and isolated in their respective worlds. For nine-year-old Ren, the last person who treated him with any form of kindness has been killed and he is shunned by what is left of his family. With no parents, no real family, and no place to go, Ren escapes into the confusing streets and alleyways of Shibuya. Through the twists and turns of the alleys, Ren stumbles into the intimidating Kumatetsu, who leads him to the beast realm of Shibuten.

For Kumatetsu, the boy represents a chance for him to become a candidate to replace the Lord of the realm once he retires. While nearly unmatched in combat, Kumatetsu's chilly persona leaves him with no disciples to teach and no way to prove he is worthy of becoming the Lord's successor. 

While the two share different goals, they agree to help each other in order to reach them. Kumatetsu searches for recognition; Ren, now known as Kyuuta, searches for the home he never had. As the years pass by, it starts to become apparent that the two are helping each other in more ways than they had originally thought. Perhaps there has always been less of a difference between them, a boy and a beast, than either of the two ever realized.

[Written by MAL Rewrite]

The story is set in Shahalta, a tiny European city-state floating in the air with practically no contact with the outside world for years. The government is transitioning from a monarchy to a republic, and to celebrate the occasion, a national treasure exhibition is being held. Lupin infiltrates the exhibition for the secret royal treasures, but not before sky pirates snatch them first.

(Source: ANN)

Lupin has become a suspect in the murder of a professor named Theo Argent. The professor had just discovered the missing page of Marco Polo's Record of Observations of the East travel journal. As Lupin is being pursued by the police, he ends up getting unlikely help from the granddaughter of Theo Argent, Lisa. 

(Source: ANN)

Lupin, Goemon, and Jigen take a mini-helicopter and head to the mysterious “Drifting Island” looking for a treasure rumored to be hidden somewhere on it. Through their exploration of the island, the trio encounters the lethal “Nanomachine,” the island’s security system. The trio triggers the alarm, springing “the Nanomachine” to life. The key to solving the island’s mystery lies in the small nation of Zufu. This once prosperous nation is now ruled by the ruthless, knife-collecting, General Headhunter. Fujiko does her usual probing and hacks into General Headhunter’s computer hoping to find some crucial information. Zenigata has received a video message from Lupin in which Lupin announces his desire for the priceless treasure. Oleander, a fiery blond officer with some hidden secrets of her own, steps in to help Zenigata. Armed with their newly found information, Lupin, Goemon, Jigen, and Fujiko go back to “Drifting Island,” but this time they are followed by General Headhunter.

(Source: ANN)