Gintoki is summoned to Yoshiwara to meet the most famous courtesan in the district. This meeting will spark a series of events that will lead him and others to confront the most powerful man in the country, the previous Shogun, Tokugawa Sada Sada.
In a flashback, a woman told her lover how much she hates the moon, a reminder of the strictly nightly visits the two conducted together. She wished both the moon and her lover can stay forever. The lover told the courtesan that he will help her leave this red light district. On the next full moon, they will meet under a sakura tree so they can flee. To complete the promise, both pulled off a strand of their hair to tie around each other's pinkies and swore to keep it.
In the present, on a night in Yoshiwara, Tsukuyo and Hinowa tell Gintoki about the legendary courtesan, Suzuran. She was famous for her beauty, dance, and song, leading many powerful officials to clamor for her company. A disappointed Gintoki wishes to meet the previous lady of Yoshiwara but Hinowa reveals that Suzuran was the reason for the samurai's presence in the autonomous red light district. A thank you for saving the district from Housen's iron fists. Later, in the service room, Tsukuyo berates an overenthusiastic Gintoki for his over preparedness, telling him that nothing beyond greetings will happen. When Suzuran's arrival is announced, Gintoki eagerly awaits... just to see an elderly, sickly woman revealed to be Suzuran. Her poor attempts at being a hostess to Gintoki results in her having a stroke and placed on a hospital bed. She thanks Gintoki for being her last customer and caring about her deteriorating condition. She then pulls off a strand of her hair to tie it around GIntoki's pinky as a promise to meet her again in the next full moon, surprising both Gintoki and Tsukuyo, along with showing her own pinky promise.
Later, Hinowa tells Gintoki and Tsukuyo about this promise, called a lover's pact. It was a vow of love between the Yoshiwara courtesans and their customers, where they offer their hair, nails and blood to seal the deal. In reality, this pact was more to extort more money from the customers. They noted that Suzuran still had this pact on her pinky and Hinowa reveals that she had made a promise to someone decades ago and refused to leave Yoshiwara despite her freedom. Tsukuyo is surprised that the courtesan has been faithfully waiting all this time. Hinowa didn't know but admits that this district is known for its dreams and lies, where some people will refuse to believe in reality.
The next day, the Yorozuya and Hyakka independently search for information on who the promise man is. Tsukuyo and Gintoki try to desperately deny that they were moved by Suzuran's story. But their respective groups reveal that Suzuran was no longer able to serve her wealthy customers due to being chosen to serve a certain man, whom they believe is the promise man... the former Shogun! While watching the palace, the Yorozuya and Tsukuyo struggle to find a way inside and to make matters worse, there was a high increase of guards. Shinpachi states that the previous Shogun, Sada Sada, had Suzuran before becoming Shogun and was the man behind the controversial decision to open Japan to the Amanto. Angered at how Sada Sada had used the old woman, Tsukuyo is determined to punish him. Kagura suddenly interrupts the talk with an idea.
Gintoki, Shinpachi and Tsukuyo stand stunned as they learn that Kagura was friends with the current Shogun's younger sister, Soyo, resulting in them easily entering the palace. After introductions, the group is sneaked in; Soyo reveals that because of a string of attacks on bakufu officials, the palace was under martial law. To the visitors' (especially Gintoki's) surprise, the Mimawarigumi leader, Sasaki Isaburo, appears and allows the princess to do as she pleases, along with giving Gintoki a new phone and hinting that the assailant was a Joui. The princess' retainer, the one-armed, elderly Rotten Maizo, tries and fails to tell the girls to play quietly and to make matters worse, Isaburo texts Gintoki that one of the Mimawarigumi, Nobume, was also watching the princess. Tsukuyo decides that they should play "Kick the Can" to distract the protectors and be able to move around the building freely. The group decides that the protesting Gintoki should kick the can far enough. In anger, he kicks the can as hard as he could. Unfortunately, under Gintoki's horrified gaze, the current Shogun, Shige Shige, appears in the can's trajectory, resulting in being beaned by the can.
- Sasaki Isaburo
- Imai Nobume
- Tokugawa Soyo
- Rotten Maizou (debut)
- Suzuran (debut)
- Tokugawa Shige Shige