Onimusha: Warlords Walkthrough Part 2: Castle Keep (Osric Boss Fight)

Having descended into the castle's moat, Samanosuke ends up encountering a monster that kidnapped Yuki and nearly killed him, proceeding to engage it in a fight that ends with the monster slain. Proceeding deeper into the moat, he ends up making his way into what appears to be an improvised laboratory where he encounters another monster which appears to be operating on the corpse. As he confronts it, the monster reveals that he is an scientist belonging to the demonkind that attacked the castle and that he was personally responsible for both creating the creatures rampaging the area and resurrecting Nobunaga Oda after his death as the warlord allegedly swore eternal fealty to the demons in an exchange for both his life and power to continue his conquest, a notion which Samanosuke initially refuses to believe. As he retreats, the demon unleashes his latest creation; An monster made from common earthworm to kill Samanosuke although he ends up killing it and leaving the laboratory, ultimately returning to the front of the castle's keep and entering it, quickly finding it full of soldiers massacred by the attacking demons. Progressing deeper inside, Samanosuke finds a man attempting to restrain an struggling young boy but fails as the boy breaks free and escapes. Intervening before the man is able to set off after him, Samanosuke questions him about his intentions for the boy and discovers that the man is in fact Tokichiro Kinoshita, an retainer working for Oda Clan who, recognizing Samanosuke, attempts to recruit him, claiming that Oda Clan would benefit from a man of his combat prowess, although Samanosuke rebuffs his request. As he continues to navigate the keep, Samanosuke finds the scrolls chronicling the attempts of Oni's previous champion and his assistant to stop the demons' incursions that led to the champion's death as he sacrificed himself to seal the cave from which demons emerged to kidnap people who were then eaten and used in dark rituals to create new demons while his assistant ended up returning to the cave and observed demons' obscene rituals first-hand, describing them on parchment before succumbing to his own injuries and also discovers the journal written by the demonic scientist he had encountered in the castle's moat, implying that the demons now scouring the region have been at their work for multiple millennia, having also been involved with and assisted other famed conquerors from the west, including Mongol warlord Genghis Khan and ancient Macedonian ruler Alexander The Great. Eventually, Samanosuke runs into Kaede as she also pursues the mysterious boy and helps her corner him. Finally able to ask him who he is and what is he doing in the castle besieged by demons, Samanosuke discovers that the boy is named Yumemaru, but he refuses to answer when asked about his reasons for being in the castle or what Tokichiro wanted from him and runs off again. While Kaede sets off after him again, Samanosuke proceeds deeper into the keep and eventually meets up with her once more, finding out that Yumemaru was originally an child of the peasant family that was massacred during an military skirmish four years earlier, leaving him orpahaned and that he was eventually found wandering by Yuki and adopted as her younger brother, making Samanosuke realize that he likely smuggled himself into the castle in an attempt to rescue his adoptive sister but leaving the reasons for Tokichiro's attempt to capture him a mystery. After navigating through a series of traps near the top of the keep, two separate again with Samanosuke heading into an chamber at the very top of the keep where he sees Yumemaru being carried off by one of the demons. As he sets off to pursue, Samanosuke is cut off by Tokichiro who finally reveals to be in league with the demons who resurrected Oda and that he isn't opposed to or disgusted by the prospect of Japan and possibly wider world becoming an massive feeding ground for demons under Nobunaga Oda's sponsorship, seeing it merely as an natural extension of the existing order within Japanese society where weaker are subordinated to the stronger. He also reveals that demons' ultimate plan for Yuki is for her to be killed and her blood to be used in an ceremony that will give Oda the power needed to continue his conquest and crush Saito Clan, retreating before Samanosuke is able to strike him down. Aware that Yumemaru will also likely be used in an sacrifice somehow, he sets off to find and rescue him...