Toshizō Hijikata served as Vice-Commander of the Shinsengumi, a special police force active during Japan's Bakumatsu period in the late Edo era. His strict enforcement of the group's regulations and fierce leadership earned him the nickname "Demon Vice-Commander." Hijikata died at age 34 from a gunshot wound during the Battle of Hakodate in 1869, the conflict that ended the Boshin War, occurring in Hakodate, Hokkaido.

Within this story, Hijikata's legacy centers on two wakizashi swords historically linked to him. These swords, crafted by the swordsmith Eitatsu Higashikubo, were stored in an Onoe family warehouse in Hakodate. They became the target of Kaito Kid, whose attempt to steal them despite his usual focus on jewels drew detectives Conan Edogawa and Heiji Hattori. The swords served as critical clues to a hidden treasure concealed by Keizaburo Onoe, the Onoe family patriarch, in Hakodate during World War II. Rumored to be a powerful war-altering weapon, the treasure's location could only be deciphered using specific swords forged by Higashikubo, including Hijikata's wakizashi.

The swords feature a pentagram-shaped design on their crossguards. This motif proved instrumental in locating the treasure. The method involved aligning the pentagram on a sword's crossguard with the star-shaped layout of the Goryōkaku fort, also known as the Hakodate Pentagram, when viewed from above from a hot-air balloon. Vertically aligning the sword at the correct height would reveal the treasure's location on Mount Hakodate.

The arms dealer Brian D. Kadokura also sought Hijikata's swords, believing they would lead him to the Onoe family's weapon. His pursuit culminated in violent confrontations, including a murder in Hakodate's warehouse district where the victim bore a cross-shaped wound, echoing Hijikata's historical sword techniques.