A Vietnam War Veteran in the World of Conan

One heroine + cameos from other anime. Nightingale died just before an operation could succeed, on foreign soil far from home. To avenge Nightingale, the Flower Country launched a campaign of retaliation against the Black Organization. A group of scouts from the Vietnam War was temporarily assigned to the operation, and Chen Jixian was one of them. When Chen Jixian learned that Nightingale was his older brother, he decided to avenge him despite the fact that they had never met. Ignoring his family's pleas, he went alone to Tokyo to seek revenge. Along the way, he met a group of people with very different personalities. Meanwhile, the Black Organization's dark forces began closing in on them. A showdown between a top assassin from the jungles of Vietnam and a transnational criminal organization with half a century of history was about to begin.