One Punch Man 2nd Season's commemorative recap special.

Oda Nobunaga saves a girl from drowning one day. She clumsily tells him that she's a shinobi. Instead of attempting to kill him, she swears to serve him one day after hearing his plans to unify Japan. (Source: Crunchyroll)

It is the year 2201. The Yamato has returned from the devastating battle with Emperor Zordar and the Comet Empire. Sanada, Aihara, and Shima are released from the hospital, and go to pay their respects to the fallen crew members at Okita's memorial. They meet Tokugawa's son Tasuke, who says that he will be joining the crew once he graduates from cadet school. The next day at his graduation, he ends up capsizing a boat full of new cadets because they are all too busy staring at the Yamato to watch where they are going. After some problems during launch due to the new engine crew hitting the wrong switches and stalling the ship, the Yamato departs on what should be a simple training mission.

The series is set during the Edo period, in the Fukagawa ward of old Edo (present-day Tokyo). Because the area is prone to fire and flooding, residents rent everyday items like pots, futons, and clothing from shops instead of purchasing them, so as not to impede them when they flee. Obeni and Seiji, an older sister and younger brother, run one such rental shop called Izumoya. However, mixed in with their inventory are tsukumogami, objects that have turned into spirits after a hundred years of existence. The siblings sometimes lend these sentient items to customers. Both Obeni and Seiji can see and talk to these spirits, and other tsukumogami often come to the store after hearing of the famed siblings. (Source: ANN)