Lesson 539 is the 539th chapter of the Gintama series.
In a flashback, as Sasaki read his wife's email, a young Nobume (still known as Mukuro) ate donut on a roof above his head. There, he received several children from the Tendoshuu. They were actually assassins from Naraku sent to kill the Hitotsubashi family, with Mukuro being the best of them. Mukuro noted to a shocked Sasaki that, while she was a child, she could kill people, and while he could kill people, he was worrying about the name of his unborn child.
At present, Saitou and Elizabeth tried to bring their leaders out of the battlefield, while Hijikata and Sasaki continued fighting. Back at the rock wall, Oboro noted that men do not know how to give up, asking Gintoki if he had inherited the will of Shige Shige and Takasugi. He also noted that the purpose of Sasaki's actions were neither to protect the new regime nor his own status, much to Gintoki's surprise.
In another flashback, Sasaki received the plan to assassinate the Hitotsubashi family, recalling his conversation with Matsudaira about being the real samurai and Mukuro's words. Meanwhile, a child distracted the Shinsengumi and, inadvertently, informed them about the Jouishishi around the place. He then ran to the palanquin and, instead of killing the person inside it, gave an erotic magazine to him. To a surprised Shinsengumi, the child admitted that Sasaki had told him to do so for a big reward. Instantly, the Jouishishi ambushed them.
As the Shinsengumi fought against the Joui ronin, it was revealed that the person inside the palanquin was Matsudaira. Beforehand, Sasaki had rumored about the Hitotsubashis' expedition to the Joui ronin, using their attack to prevent the assassination. According to the plan, even if the assassination took place and Matsudaira died, the Shinsengumi could not be blamed, as long as they survived the ambush. Though, Sasaki denied helping Matsudaira and mailed his wife the name of his child, who was born a girl. Unbeknownst to the Mimawarigumi's chief, Oboro had learnt of his betrayal at the same time and a punishment for him was ordered.
At present, upon learning of Sasaki's actions, a surprised Okita found out that he had saved the Shinsengumi. Nobume added that he also tried to save the children as well, yet no one could save him. Back in the past, unable to send the email, Sasaki rushed to his wife's place, only to see her, as well as his daughter, dead under Mukuro's hand. In the mail to his wife, the name of his daughter was "Nobume."
Characters in order of appearance
- Oboro: The Shogun has died and Takasugi has disappeared. But like you have inherited Shige Shige's will, it would appear you have inherited Takasugi's will as well?
- Imai Nobume: I think that back then, Isaburo tried to save... the children as well... but there was no one there... to save Isaburo. No one could save him.
- Sasaki Isaburo: (To his wife) I finally came up with a good name. This time I'm sure you will like it too. When will I get there? Please email me when I get close. Or even if I'm far. Please email me. I'll go meet you wherever you are. You and Nobume.