Donten ni Warau Gaiden: Ouka, Tenbou no Kakehashi                                
                                
                                    Donten: Laughing Under the Clouds - Gaiden: Chapter 3 - Conspiracy of the Military                                
                            
                            
                            
                                
                                    
                                        The three brothers discover that the human experiment banned after destroying the "Orochi", is still going on to secretly revive the evil snake. They also...                                    
 
                                 
                                
                                    
                                        The three brothers discover that the human experiment banned after destroying the "Orochi", is still going on to secretly revive the evil snake. They also find out that some ex-members of the Yamainu (the Japanese military unit formed to kill the snake) are behind this conspiracy. The brothers fight together again in a battle against the military.
(Source: Amazon Prime Video)