Sengoku Musou SP ~Sanada no Shou~ (戦国無双SP ～真田の章～) is the first animated production for a Warriors IP and one of the projects which celebrates the tenth anniversary of the Samurai Warriors series. It serves as a prequel to Sengoku Musou. Samurai Warriors 4 music and voice actors are reused in the TV special.
The narrative roughly dramatizes events leading up to the first Ueda Castle siege. Consumers who purchased the The Treasure Box or Anime Box editions of the fourth title received postcards drawn in the animated style and three minutes of new footage not seen in the TV broadcast.
The limited edition Blu-ray/DVD Gamecity Set includes an exclusive tapestry, hand towel, and mug with the purchase.
Cast listing is for the Blu-ray version.
- Takeshi Kusao - Yukimura Sanada
- Daisuke Ono - Nobuyuki Sanada
- Eiji Takemoto - Mitsunari Ishida
- Masaya Takatsuka - Kanetsugu Naoe
- Yuko Nagashima - Kunoichi
- Joji Nakata - Ieyasu Tokugawa
- Akio Otsuka - Tadakatsu Honda
- Makiko Ohmoto - Inahime
- Ryota Takeuchi - Kagekatsu Uesugi
- Yuka Saito - Yukimura Sanada (child)
- Jun Shikano - Nobuyuki Sanada (child)
- Manabu Sakamaki, Riki Kagami - Sanada retainers
- Takashi Matsuyama, Masami Iwasaki - Tokugawa warriors
- Seiji Katou, Suguru Inoue - Foot soldiers
- Suzune Okabe - Messenger
- Jyurohta Kosugi - Nobunaga Oda
- Unsho Ishizuka - Narration
- Performed by Kuroyume
Blu-ray additions are highlighted in orange to distinguish from the original TV broadcast.
The narration introduces setting of an era of endless warfare between rival clans. Among them is Shingen who died with his dreams unfulfilled. A few scenes from Nagashino are reenacted for viewers, and the Sanada brothers charge through the Oda-Tokugawa infantry. Nobunaga duels them before the narration skips to the Takeda's fall at Tenmokuzan. The Sanada brothers have barely fled the Takeda's destruction.
Yukimura, upset to have failed his duties to protect his lord's legacy, feels his clan no longer has a purpose. Before Nobuyuki can present a counter argument, Kunoichi reports that Oda headhunters are close on their tail. Yukimura immediately charges to slay them and unknowingly runs into their line of fire. Nobuyuki saves him before they can fire and patronizes his younger brother for his recklessness. When Yukimura proclaims that their crest gives them the courage to die at any time, Nobuyuki counters that it is the seal of survival and their right to carry on the Takeda's dream.
Events afterwards (Honnōji, Yamazaki, and Hideyoshi's rising power) are abbreviated to hop to Ueda Castle's completed fortifications. The Sanada brothers watch over its inhabitants yet the younger brother feels his brother is worried about something. He trains underneath a cheery tree and chats with Kunoichi about current affairs, remarking that the Sanada are currently surrounded by three major foes (Tokugawa, Hōjō, and Uesugi). Looking up at the branches above reminds him of their childhood training. A younger Yukimura bests the older brother during their sparring so Nobuyuki congratulates him. Yukimura rejoices since he wishes to fight for Shingen as soon as possible. Nobuyuki warns him about the Uesugi, noting that their generous salt offering to the Takeda is a true show of their power. The older brother instructs Yukimura that military strength isn't everything in the world.
To help his older brother, Yukimura volunteers to be sent as a political hostage to the Uesugi. If successful, their alliance could be used to protect their clan from a rear assault. Nobuyuki, despite his personal inhibitions over parting with his brother, agrees and fondly watches his brother's departure. Yukimura is surprised when Kunoichi accompanies him.
Yukimura travels to Kasugayama Castle and attends an audience with Kagekatsu. His unflinching gaze and composure impresses Kagekatsu enough to agree to the Sanada hostage. Kanetsugu interprets his lord's praise for the confused Yukimura, quickly introducing him to his friend and guest, Mitsunari. Mitsunari surmises the Uesugi's approval occurred due to Sanada's previous ties to the Takeda.
Meanwhile, the Tokugawa army have taken note of Yukimura's departure. With the brothers separated, Ieyasu sends emissaries to Ueda Castle with a command to surrender Numata Castle to the Hōjō. Nobuyuki figures that the Hōjō and Tokugawa have allied with one another. The inquiry leads the Sanada lord to ponder Ieyasu's true character, remembering his callousness towards his courageous soldiers due to his experience at Mikatagahara. Yukimura learns about the same inquiry from Mitsunari while he is badmouthing Ieyasu's proceedings. When the skeptic wonders if the Sanada will fight to the death, Yukimura has faith his brother would do what's best for their family's survival.
Nobuyuki ponders his decision while taking a leisurely horse ride near the castle. During sunset, Inahime stops by a nearby river to cool herself until Nobuyuki approaches. He apologizes for his intrusion and their brief introductions leads to the maiden inquiring about his hesitation to answer. She believes her lord's judgment is fair and necessary for protecting the Sanada's future; if he fails to comply, the Tokugawa army will invade them. Inahime discerns that he cannot comprehend her lord's fight for the greater good over personal gain yet doesn't elaborate for him. Nobuyuki protests that giving in will betray the will of his ancestors and his clan's being. Their conversation ends with his staunch decision to refuse the Tokugawa's command. He reflects that the retainers' faith for Ieyasu's heart may have been the cause for their die-hard loyalty to him.
Inahime delivers the Sanada lord's answer, and a castle siege commences. Kunoichi reports to Yukimura that the Sanada defenders are outnumbered three to one. Yukimura makes preparations to leave at once. Kanetsugu and Mitsunari attempt to stop him. Kanetsugu states the Sanada have no chance at victory; Yukimura questions if he could stand idly by and allow the dishonorable Ieyasu to succeed to silence him. Mitsunari reminds him that the Uesugi could attack if he goes, making his trip to become a hostage pointless. Yukimura has faith in the pledge to protect his family with his brother. Although the duo insists he will die, Yukimura thanks them and Kagekatsu for his wonderful stay and rides away.
Nobuyuki commands the defenses with the Sanada troops, repels the initial Tokugawa charge, and orders the Sanada army to lead an offensive. They appear to divide the main Tokugawa into three battalions, yet this was a ruse to lure the Sanada into Tadakatsu's unit. Sanada morale appears bleak until Yukimura returns to Ueda Castle. He is surprised when Kanetsugu and Mitsunari reinforce him, turning the tide towards his family's favor. Yukimura duels Tadakatsu to spare his family's men.
Nobuyuki personally charges into the fray to slay Ieyasu. While their weapons are stuck in a deadlock, Ieyasu shouts for the youth to consider the future beyond this battle. The wars will continue endlessly at their current rate, yet the Tokugawa lord is willing to do whatever it takes to end them. Ieyasu feels that the strong youth, like Nobuyuki, has the power of realizing the dawn of an era of peace with him. Only after meeting him does Nobuyuki feel he has no chance of destroying Ieyasu's power for his dream. The arrival of the main Uesugi forces cuts off their conversation. As he orders for the Tokugawa's retreat, Ieyasu gives a parting wish for Nobuyuki to survive the wars.
Back at Ueda Castle, Yukimura thanks his friends for coming. Kanetsugu insists they were moved by honor and ushers for the duo to join him for an oath in honor. The Sanada brothers reunite afterwards, the older brother chastising the younger brother for nulling the purpose of being a political hostage and returning to Ueda Castle. Yet Nobuyuki warmly commends him since his actions saved everyone. The Sanada brothers agree to keep protecting their home together. While fireflies spontaneously surround them, Nobuyuki's last comment suggests he has renewed faith in the world Ieyasu can create.
After the credits, the audience is informed of Hideyoshi's death. The land is split again due to tensions leading towards the Sekigahara conflict. The narration states the fate of the Sanada brothers is engulfed within the struggle.