John Klause operates under the alias "Jean Claude" as the leader of the international arms smuggling syndicate Shot Shell. He orchestrates illegal weapons deals and global provocations from a secret Pacific island base equipped with advanced hologram technology, using it to deceive adversaries like Lupin III without physical exposure. Shot Shell embeds agents worldwide to deliberately instigate conflicts and wars, creating demand for its arms supply. Klause targets the stolen Russian nuclear submarine Ivanov from Lupin's gang to escalate his operations, planning to harness its nuclear capabilities for broader destabilization.

When Fujiko Mine infiltrates Shot Shell as part of Lupin's scheme, Klause develops a romantic interest in her. This attraction lowers his guard during a critical confrontation, allowing Fujiko to disarm him and exploit his vulnerability to aid her escape. Klause's plans unravel during an assault on his base by Lupin's gang and Inspector Zenigata. His alliance with corrupt ICPO agent Keith Hayden fails to eliminate the thieves, and the submarine is destroyed to prevent misuse. Klause's fate remains unspecified after his operations collapse.