You're a convict for a crime that you were framed for. But instead of being executed, you were sent to an island to get something called the Elixir of Life for the shogun.

While walking on the island, a giant monster appears. You were ready to fight but out of nowhere, a giant axe was thrown into the monster and killed it.

"Strike!"

You look over to see another convict, Chobei Aza.