The end of the Edo period, the Bakumatsu (between 1853 and 1867), was an era of uncertainty and chaos, a time when the line between right and wrong was indistinguishable. During this era, Hijikata Toushizou, determined to live by his own rules, led his reformed Shinsengumi--formerly a ragtag group of mercenaries that became the elite Samurai fighting force of the shogunate--to glory. This is the story of his life.

Shiina Atsushi, a Japanese-American boy, lives in Japan during WWII. He comes across a Chinese girl, collapsed among the debris of a collapsed building, with a strange glowing symbol on her back. She claims she's from another world that has been destroyed. As she attempts to leave, the military arrive and demand she go with them. Who is this mysterious girl? What will young Atsushi do?