|This article is about a/an giant monster in Choudenshi Bioman.|
It is a huge Mecha-Gigan with a trident as its main weapon.
Neptune Canth is a Mecha-Gigan sent as a final defense by Doctor Man to defend a device set up in a children's hospital by Farah that expands magma to the point that it would cause both a volcanic eruption and a massive earthquake 6 hours after activation. After a short battle, Bioman destroy the Mecha-Gigan with Reverse Straight Line Cut from Super Maser.
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