Takarajima

Jim Hawkins is a young boy lead by progressive events to embark on a search journey for the legendary treasure of the once dreaded pirate, Captain Flint. On their way to Treasure Island, John Silver, Jim's best friend, take over command of the ship revealing his true self as the ruthless pirate who once was the right hand of Flint himself. Feeling betrayed, Jim now has to deal with his mixed feelings and face Silver who still consider himself and Jim as friends. (Source: ANN)

This is an anime adaptation of the classic novel "Treasure Island" written by Scottish novelist Robert Louis Stevenson in 1882.