Set in the years following World War I, The Phantom Thief Bat Baron follows the exploits of a mysterious gentleman thief known as Baron Bat. Operating in a Europe still bearing the scars of recent conflict, this enigmatic figure targets the wealthy and corrupt, stealing not for personal gain but to aid the weak and downtrodden. The narrative blends suspense with comedic elements as Baron Bat executes elaborate heists, often outwitting authorities and criminals alike while maintaining his secret identity.

The central character, Baron Bat, is portrayed as a charismatic and cunning figure whose true name and background remain largely concealed. His adventures pit him against various antagonists, including law enforcement figures trying to unmask him and rival criminals with more sinister intentions. The tone balances thrilling escapades with lighter moments, fitting its description as a suspense comedy series from the late 1960s.

The original 1967 serialization in Kodansha’s Shōjo Friend magazine marked the first part of the series. Subsequent chapters continued in other publications, including the second part titled Dr. Asimov no Karei na Bōken (The Brilliant Adventures of Dr. Asimov) in Shueisha’s Shūkan Seventeen magazine in 1969, and the third part titled Kaitō Shinshi Asimov Kyōju no Kareina Bōken (The Gentleman Thief: The Brilliant Adventures of Professor Asimov) in Shogakukan’s Shūkan Shōjo Comic in 1973. These later installments suggest an evolution in the protagonist’s alias or identity.

Notable narrative arcs and additional stories include three one-shot works that accompany the main series: The Strange Story of Elsinore Castle, Lord Monsieur’s Great Plan, and The Beautiful Vampire. These stories expand the world of Baron Bat, introducing gothic elements and further adventures that complement the central premise of a heroic phantom thief operating in a post-war European setting.