Flower Sleeping in the Sea.

The young pirate head Sakaki met the autistic but beautiful samurai Murou... Why did Murou have the other half of the treasure island map left by Sakaki's grandfather? Why did Murou keep to himself? Could Sakaki open Murou's closed heart? And how should he handle his best friend who loved him, Juurou? (Source: Outou Shobou, translated)