In the year 2205, a special sage known as Saniwa has the ability to breathe life into inanimate objects. At the same time, dark forces have initiated a plot to travel back in time and change the course of history—and the only ones capable of stopping them are the Saniwa and their strongest animations: historical Japanese swords, in the form of handsome young men.

Touken Ranbu: Hanamaru opens on the life of Yamatonokami Yasusada, Souji Okita's beloved uchigatana, as he begins his first day at the Saniwa's citadel. Soon reuniting with his old friend, Kashuu Kiyomitsu, the two are caught up in the daily antics of their fellow sword warriors. They never miss an opportunity to have fun, whether it be through wild snowball fights or introducing their newest comrades to the citadel. Of course, when the government calls, the swords are always ready to fulfill their mission of protecting history.