Shizumaru is a young boy who has no memory of his past. He doesn't even remember his name, so he named himself with a sword. Because he was regarded as a "devil's child" since he was a child, he lives and lives alone. The only thing Shizumaru remembers is the devil's field of vision and the red field of vision. In order to figure out what happened, he traveled around Japan to find the demons. While he eventually found Zankuro and killed the demon. But after he killed Zankuro, he realized his inner demons. Soon after, he once again felt the spirit of Zankuro in Amakusa. In order to kill Zankuro, he went to Amakusa Castle.
During the events of Samurai Shodown V, he was treated as a servant by a pair of noble young couples. The husband left the battle in Hinowa and leave his wife Hakana under the protection of Shizumaru. In pregnancy, Hakana wants to return to her father's refuge (Shizumaru does not know is Youkai Kusaregedo). Shizumaru, to ensure that she is safe, feels obligated to help the war. After the battle, his efforts will receive huge bonuses. He left home but was stopped by a man called Yaiba. Although Shizumaru denied that the man insisted that he was Yaiba and that "his family" missed him. Shizumaru chose to stay with his master and flee. Unfortunately, his master died in the war, and Hakana was eaten by her father. Because of the trauma he suffered, he marked any malicious things, both human and behavior, as "devils."
Shizumaru respects Haohmaru, he encourages him, and teaches his sword philosophy at an early age. Shizumaru tried to defeat Zankuro and reportedly avenged his family's death. He and Zaohmaru killed Zankuro. After the events of Samurai Shodown IV, he confused the remaining blood desires with a "rampaging demon." However, he began to accept his "devil" as part of himself and to live in peace with his past.
- Shizumaru was originally believed to be loosely based off of Himura Kenshin from the manga Rurouni Kenshin, but the creators stated that his visual model was Kurama from Yu Yu Hakusho.