A warrior, seduced by the authority he promised, causes harm to his baby son. The son, destined to defeat the 48 Fiends, had 48 body parts ripped from him, one by one by each demon. The samurai casts the remnants into a river, where a sympathetic doctor discovers the still-living infant. Following the child’s upbringing, the doctor performs surgery on him, replacing missing parts with mechanical ones. Knowing what is in store for the youngster, the doctor returns his missing arms with sword arms, attaches a repeating rifle to one arm, and a cannon to one leg. The game opens with Hyakkimaru, now an adult, embarking on a quest to retrieve his body parts from the Fiends. Dororo, a kid robber, soon joins them on a journey against ancient Japanese demons and the monsters they produce.
Blood Will Tell an action game in which the player controls Hyakkimaru, a man whose bodily parts were stolen as a child by demons. His goal is to reclaim each of his physical parts, which allows him to boost numbers like HP and power while providing optional extra capabilities (for example, the eye displays the game in color, while the voice chords allow him to speak). Hyakkimaru wields a sword that he may use to fight adversaries, but he can also switch to his two more miniature swords hidden within his arms. The swords level up and gain power as he uses them. Hyakkimaru can also charge up a sword attack and enter a series of button pushes for combos if unleashed at the right time. If the enemy is killed during this combo, the player can use the Triangle button to perform a finishing move that can yield extra goodies ranging from health items to swords.
Hyakkimaru also has a repeating gun and a cannon in his leg. While these are extremely powerful, they each require ammunition and cannot be used without it. The pistol can be fired at opponents quickly, whereas the cannon must be charged and aimed for a strong shot. Unlike his swords, which must be utilized at close quarters, both have the advantage of being long-range weaponry.
At one point in the game, Hyakkimaru encounters the kid thief, Dororo. Dororo frequently supports Hyakkimaru during combat and can be given commands such as “fight,” “evade,” “collect items,” or “search.” The couple will occasionally split off, and Dororo will be playable independently. The thief pulls switches to activate puzzles, avoids traps, and steals stuff in these portions, which are more puzzle-based. Dororo can toss pebbles from a distance and later obtains more lethal smoke bombs.
