After losing his home to a powerful enemy, a hot-tempered fighter trains under his zealous grandfather while awaiting his chance for revenge.

It is a cross over between the series Lupin III and Case Closed and takes place after the television special Lupin the 3rd vs Detective Conan, additionally incorporating various elements from its predecessor in its plot. The plot follows Conan Edogawa who sets out to apprehend Arsene Lupin III, the suspect of stealing a jewel called Cherry Sapphire.

A strange boy named Tsukasa appears in the online video game "The World". He claims to be alive, and without a computer.