The Pirate Hunter Arc (海賊狩り編, Kaizoku Kari-hen) is the final story arc in Mouretsu Pirates and the second anime-only arc. A series of attacks are made against Letter of Marque holders by a pirate hunter utilising a highly advanced warship, leading to the first Pirate's Council since the War of Independence.
A series of attacks on frontier pirate ships by an unknown pirate hunter has been occurring, with the Silver Fox the latest to fall victim. In response to this and considering her circumstances with both the Letter of Marque conditions and her exams to deal with, Marika, who has just been nominated as Lynn's replacement as president of the yacht club, arranges with Show to have the Bentenmaru escort another pirate ship, the Big Catch, in order to give them both extra protection against the pirate hunter .
During the mission however, an unknown vessel touches down in front of them. Against Marika's advice, Captain Stone of the Big Catch engages the enemy vessel and suffers heavy damage in the process. When the Big Catch tries to retreat, both crews are stunned when the unknown ship rapidly zigzags across space to block the Big Catch's escape route before incapacitating it with a barrage of beams . Before it can target the Bentenmaru, another ship, the imperial pirate ship Parabellum arrives and drives it off. The Parabellum's captain Ironbeard then warns the Bentenmaru of the danger that frontier pirates face against the pirate hunter ship, Grand Cross. After the Parabellum leaves, the Bentenmaru crew saves the crew of the Big Catch though they are unable to save the ship .
The next day, Chiaki Kurihara transfers into Hakuoh Academy again, bringing a request from Kenjo for the Bentenmaru's assistance in forming an alliance between the Letter of Marque holding pirate ships against the pirate hunter. With help from Gruier, they deduce that the Grand Cross is likely one of several top-secret prototypes for next-generation battleships with gravity-control under development in the Galactic Empire. Chiaki also speaks of the Legendary Chef from the first Pirate's Council who was said to know a song capable of summoning the pirates together. Marika takes her to Oyaji-san, who is revealed to be the Legendary Chef's son and broadcasts the Pirate's Song into space .
As the Bentenmaru makes its way to the Pirate's Nest, it is ambushed by the Grand Cross. Following an exchange of fire, the Bentenmaru manages to escape, sustaining heavy damage in the process. Other ships also head for the Pirate's Nest with some being sunk en route. After reaching the Pirate's Nest, the Bentenmaru enters a dock for repairs and upgrades, with Coorie using her alternative look to help acquire the necessary parts. After a meeting with Kenjo Kurihara, Marika encounters the captain of the Grand Cross and after a brief confrontation, confirms suspicions of a spy aboard the Bentenmaru. At the same time, Luca confronts Kane with Misa over suspicious behavior but her own out-of-character behavior prompts Misa to shoot her, exposed her as an android imposter. Afterwards, Misa warns Kane over his own actions while another Kane looks on from afar. At the same time, unknown to Marika, Ririka heads to the Pirate's Nest with Ironbeard aboard the Parabellum .
While the crew are fearing the worst for Luca, the real Luca arrives, having returned from her holiday after a change of plans after being saved by Ririka, a fact she keeps from the rest of the crew save Kane. While Marika is meeting with Kenjo about the intruder, Quartz appears once again in the council room, wearing a black cloak with a gold skull. When the frontier pirates assemble with hostility towards the intruder, Fei reminds them of the no-killing rule of the Pirate's Nest and reveals that the skull symbolizes an imperial pirate. When Quartz declares her intention of pirate hunting in an attempt to provoke the pirates, Marika challenges her to a showdown. One of the captains, Koja, intends to kill Quartz regardless but he is stopped by the arrival of Ironbeard who has been sent to retrieve Quartz on the order of the Galactic Empire's queen. As the Pirate's Council begins, Koja slips away to assassinate Quartz but he is thwarted by Blaster Ririka. Afterwards Misa confronts Ironbeard over having his helmsman Shane switch places with his twin brother Kane, before the Parabellum leaves the Pirate's Nest. After the successful Pirate's Council, the pirate join forces with the upgraded Bentenmaru chosen to lead their electronic warfare efforts, issuing a song of challenge to the Grand Cross .
Reaching the chosen location, where the Bentenmaru had previously encountered the Golden Ghost Ship, the frontier pirate fleet finds themselves up against three Grand Crosses. With Coorie coordinating their synchronized electronic warfare, the pirates hold their own against the Grand Crosses in electronic warfare. When one of the enemies zigzags, the pirates anticipate its movement and trap it within a chaff field before destroying it with a heavy missile barrage. Another Grand Cross is destroyed by the Barbaroosa's arms pack, and the pirates focus fire on the remaining ship. In anger, Quartz targets the Bentenmaru but is rammed by the Shangri-La. Marika leads a combined boarding party onto the enemy ship and confronts Quartz in the control room. Quartz escapes while setting the Grand Cross to self-destruct. Later, the pirates celebrate their victory, while the Parabellum rendezvous with Odette II, which arrived too late to observe the battle, in order to take the yacht club home in time for exams, with Gruier meeting Ironbeard who is actually Gonzaemon Kato, having faked his death. After returning to the Sea of the Morning Star, Marika manages to pass her exams and continues into her third year as a high-school space pirate .
- A series of attacks are carried out against frontier pirates by pirate hunter Quartz Christie using the prototype battleship Grand Cross .
- The Pirate's Song is broadcast across space, heralding the first Pirate's Council since the War of Independence .
- The frontier pirates join forces to face the Grand Cross in battle .
|Episodes||22 • 23 • 24 • 25 • 26|
|Multiple||Recruitment Arc • Golden Ghost Ship Arc • Hakuoh Pirates Arc|
|Anime-Only||Nebula Cup Arc • Pirate Hunter Arc • Abyss of Hyperspace|
|Novel-Only||Three Ships Arc • Skull Star Arc • Bounty Arc • Wanted Arc • Timeslip Arc • War of Independence Arc|