Kaientai Arc is the 57th arc of the Gintama series. In this arc, the Kaientai's leader, Sakamoto Tatsuma was captured by a space pirate organization known as the Chidori. As the rescue progressed, the past of Sakamoto and Mutsu's first meeting was revealed.
During a business meeting of the Kaientai, Sakamoto introduced a bag containing 50 million yen as his latest product. In fact, it was an ordinary bag having nothing but rocks inside. Later, he used these bags to throw a party at Snack Smile to impress Oryou. Under Gintoki's instruction, Mutsu arrived and angrily threw him into the ocean in a bag.
In a pub, Mutsu and Gintoki discussed about their first meeting with Sakamoto. It was revealed that after leaving the Joui War, he was tricked and threw into the ocean, only to be picked up by a fleet of the space pirate gang Chidori, whose vice-leader was Mutsu. At present, she was informed that Sakamoto had been captured by the group again. The space pirates inquired the whole Kaientai fleet as a ransom to save Sakamoto. However, Mutsu chose to attack them and infiltrated the enemy's ship with Gintoki. As the battle against the pirate occurred, her past with Sakamoto was shown:
Ten years ago, having picked up by the Chidori as a slave, Sakamoto offered to buy the whole fleet with the slaves, which Mutsu flatly turned down. In jail, he taught her about the nature of doing business, as opposed to slave-dealing. Some time later, after her father's death, Mutsu overheard the supervisor's plan to kill her and the slaves. Moved by Sakamoto's nature, she instructed him to escape with the slaves while surrendering herself to the rebels. Nevertheless, Sakamoto refused to escape and was captured along with Mutsu. Beforehand, he had used the escape pods as a distraction and let the slaves take over the Chidori ships. As soon as the slaves fired cannons at the mothership, the two defeated the pirates and threw all of them into the ocean, thus beginning the operation of the Kaientai.
In the meantime, Mutsu pretended to be dead as soon as she reached to Sakamoto's place, where he was held hostage. Seeing her defeat, Sakamoto mocked the pirates' supervisor and angrily knocked him down upon hearing the latter's reply. Mutsu then defeated the last remnants of the Chidori, which revealed that she is a Yato, and killed the supervisor, while severely injured Sakamoto and Gintoki in the process.
Some time after the event, Mutsu sent a bag of radishes as a thanking gift for Gintoki, as the Kaientai cast off.
Characters in order of appearance
- Sakamoto Tatsuma
- Shimura Tae (cameo)
- Oryou (cameo)
- Sakata Gintoki
- Takasugi Shinsuke (flashback)
- Katsura Kotarou (flashback)
- Chidori's leader
- Shimura Shinpachi (cameo)
- Kagura (cameo)