Sakamoto Days presents its darkest character through Satoru Yotsumura, a man who murdered his own wife while his son watched in horror. This founding member of the Order bears the burden of impossible decisions that turned him from the JAA’s second-in-command into a wanted fugitive.
Yotsumura’s three-section staff has struck down both foes and family, leaving behind scars that define his life in Sakamoto Days. His tactical brilliance once shaped the assassin world's most elite organization, yet personal betrayal pushed him to obliterate everything he built to save the one person who now hates him most.
Yotsumura’s role as the former second-in-command of the Japanese Association of Assassins speaks volumes about his skill and reputation. He was also a professor emeritus of the JCC and now works against the JAA after he was banished by Sei Asaki in his takeover. This dramatic shift from respected leader to wanted fugitive forms the foundation of his character arc in Sakamoto Days.

The founding of the Order alongside Kindaka established Yotsumura as a cornerstone of the assassin world. His academic background as a JCC professor emeritus demonstrates his multifaceted role within the organization. However, his attempt to eliminate JAA executives eight years before the main storyline resulted in his banishment and a death sentence.
Perhaps the most defining moment in Yotsumura's story involves his devastating decision regarding his family. His wife, Shino, became secretly entangled in a conspiracy against the JAA chairman, using their son, Amane, as leverage. Faced with an impossible choice, Yotsumura killed his wife to protect his son, an act witnessed by young Amane.
This traumatic circumstance shaped both characters profoundly. Although Yotsumura made the ultimate sacrifice to protect his child, Amane still harbors deep resentment toward his father. The complexity of their relationship carries emotional weight in Sakamoto Days' narrative.
Prowess and Signature Weapon of Satoru Yotsumura in Sakamoto Days

Yotsumura’s combat prowess more than justifies his once high-ranking position within the JAA. His calm demeanor in battle masks incredible skill and power. He uses a three-sectioned staff and shares his weapon of choice with his son. This specialized weapon features a razor-sharp blade capable of cutting through support beams and slashing through traditional Japanese houses with ease.
His enhanced physical capabilities include superhuman strength, allowing him to dodge attacks from elite assassins like Shishiba. His durability was demonstrated remarkably during their fight, surviving building collapses and faking his death despite severe injuries. Most impressively, his reflexes enable him to eliminate multiple armed opponents without even looking at them.
The confrontation between Yotsumura and his former student Shishiba stands as an intense battle in Sakamoto Days. This fight exhibited both characters at their peak, with Yotsumura carrying his own against one of the Order's strongest members. His battles have left lasting marks, including facial scars that eerily mirror those of his former partner.
Current Role in the Sakamoto Days Story

After his presumed death and unexpected survival, Yotsumura now moves unseen, operating from the shadows. His alliance with Yoichi Nagumo represents a significant shift in the series' power dynamics. His intimate knowledge of JAA operations and connections within the assassin world makes him invaluable for intelligence gathering.
His discovery that Rion Akao placed the bounty on Sakamoto exemplifies his continued importance to the plot. As someone who understands the inner workings of both the Order and JAA, Yotsumura serves as a crucial bridge between past and present conflicts in Sakamoto Days.
In conclusion, Yotsumura's three-sectioned staff now swings in service of revolution against the very institution he helped create. His yellow eyes, dulled by trauma and betrayal, scan for threats that may never come while his son grows stronger in his absence.
Sakamoto Days has forged its most compelling antihero through Yotsumura's journey. His legacy bleeds through every chapter, proving that some wounds cut deeper than any blade.