Bakumatsu Joshikousei: Hana to Okami

Okita Sou is a girl who carries memories of the Edo-era swordsman Okita Souji.

When she enters a girls' high school, Sou finds herself reunited with others who also possess memories of past lives— Toshizou Hijikata, Isami Kondo, and the other members of the Shinsengumi, who had once fought together during the tumultuous era.

Living in the girls' dormitory, Sou must live her present life while dealing with historical memories of the Shinsengumi headquarters. Amidst this turmoil, other people bearing the memories of their arch-enemies — samurai from the Satsuma and Choushuu clans —begin to appear.

(Source: Takeshobo, translated)