Hakuoki ~Demon of the Fleeting Blossom~ A Memory of Snow Flowers

Chizuru Yukimura is a young woman who, disguised as a boy, traveled to Kyoto to search for her missing father. However, she is attacked by ronin. Just as one of the ronin is about to find her hiding place, he is attacked by demons. The demons close in on Chizuru, when she is saved by the Shinsengumi. In Shinsengumi headquarters, she explains who she is and why she is there. The Shinsengumi allow her to stay as they are looking for her father as well.

Chizuru starts to work her way into the Shinsengumi's society, motivated by a desire to be useful and concern over the injured Sannen-san. She gains permission to leave headquarters in the company of the regular patrols, in order to continue the search for her father. Following one lead, she runs headlong into the Shinsengumi's enemies, and in the subsequent fight, the Shinsengumi learn of a Choushuu plot against Kyoto and the Emperor.

The smaller squad of Shinsengumi out to apprehend the Choushuu conspirators find them at Ikedaya. Chizuru is sent with Yamazaki to update the other soldiers surveilling at Shikokuya so they can reinforce their brethren, but runs the message herself while Yamazaki fights off attackers. Back upstairs at Ikedaya, Okita and Heisuke engage with two mysterious and very powerful strangers. The Ikedaya Incident leads to a request for the Shinsengumi to fight on the front lines - the beginning of the Kinmon no Hen Incident.

A mysterious princess is introduced, speaking of a "storm" arising. Meanwhile, the Shisengumi have marched to the front lines, and leap into battle on their own accord. Cleaning up after an enemy sortie, Saitou finds one of the mystery men from Ikedaya (Amagiri Kyuuju) defending Satsuma Clan soldiers; Harada encounters a third powerful stranger (Shiranui Kyou) wielding a Western-style handgun; and Hijikata with Chizuru are confronted by the blond stranger (Chikage Kazama) as they race to Mt. Tennozan.

After several months, Chizuru's service to the Shinsegumi has become a regular part of their everyday lives. Itou Kashitarou allies with the corps as an advisor, but not all the soldiers are happy with his presence. The Shinsengumi make plans to move to a larger headquarters. Meanwhile, Yamanami, discontented with his ability to contribute, continues research on "that medicine" in a dangerous way.

The Shinsegumi wait to see if Sannan-san recovers from his violent reaction to "that medicine" - and work to keep Itou from noticing. Chizuru has a fuller truth revealed to her because of the incident. While on patrol, she and the soldiers rescue a young woman who looks almost exactly like Chizuru, who still dresses like a boy. Later, as the Shinsengumi take up guard duty for the Shōgun's visit, the three strangers - calling themselves "Oni" - try to kidnap Chizuru.