Lupin III: Chi no Kokuin - Eien no Mermaid

(Esta sinopse está em inglês. Ajude a comunidade traduzindo!)

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Two jewels are the key to the ancient treasure of Yaobikuni. But legend has it that the only person who can find the treasure is one who can walk the path of death.

And why is Lupin interested? This is the one treasure his grandfather sought but did not steal.

(Source: AniDB)