Lupin III: Island of Assassins

Zenigata arrives at the birthday party of an important politician to investigate a fake Lupin calling card. Lupin shows up as well. Suddenly, masked assassins break in and begin to shoot everything that moves. Zenigata goes after Lupin amidst all the gunfire and corners him in the courtyard of the house. Suddenly, a hand holding a Walther P-38 pops out of a window and shoots Zenigata in the chest. Lupin recognizes the Walther as his own and decides to investigate. (myanimelist.net)