This continued the search for the Hojo treasure which takes both Shintaro and the Fuma around Musashi and Sagami provinces. Shintaro now has the three mirrors but they reveal only a map hidden in a cave temple on Enoshima when placed in the appropriate slots in the wall. This map gives the location of a place called the Wind Fort. At the Wind Fort another map is found giving the location of a place called the Water Castle. At the Water Castle (a cave behind a waterfall) a map is found giving the location of the Fire Tower, an underground cavern in a plain of solfalas where the treasure is actually located. Most of this story concerned Shintaro's efforts to find these places before the Fuma did, and the Fuma's efforts to steal the maps from Shintaro. Oboro, Kotaro's sister, falls in love with Shintaro and eventually betrays the group as they near the Fire Tower. Kotaro and Shintaro duel there amongst the bubbling sulphur, until Kotaro, mortally wounded (apparently) staggers into the Fire Tower and, before Shintaro can stop him, blows up himself and the treasure.

Both this and the preceding story made much use of music to underscore mood. Not only was the theme used almost as a leitmotiv within episodes for Shintaro, but there was a poignant song, first heard in the previous story's "Musai's Curse" about the heartless ultimately futile life of a ninja (sung by Saga Naoko) which was Oboro's theme, especially whenever she considered her dilemma: her loyalty to her brother, her love for Shintaro, her concern at her brother's plans which she believed would destroy the Fuma. Saga Naoko was a pop singer on loan from King Records.

"Shintaro, Tonbei and Shusaku have the three mirrors which they use to uncover a map of the Wind Fort in a cave temple. Watching them is Jinkuro the Owl, a Fuma ninja, supposedly drowned with the rest. Disguised as a blind masseur he comes to the inn where Tonbei, Shintaro and Shusaku are staying, poisons Tonbei with a herb which causes paralysis then death and tries to force him to draw the map, which he had memorised. He is foiled because Shintaro, suspecting something like this would happen, had Tonbei unwittingly memorise a false map. Jinkuro is killed in a duel." At the end Kotaro's sinister laugh is heard as Shintaro and co. realise he isn't dead after all. "Fuma are the wind. Beware, we shall come in the night, we shall come in the day and we shall get the map of that secret treasure - Fuma Kotaro is a deathless ninja," he warns them.

"Kotaro recovering from the wound he received in the duel with Shintaro (at the end of "The Secret Cave") is forced to stop at Hachioji to recuperate. He sends Hakuro Genki after Shintaro. Genki disguises himself as Tonbei and attacks the police forces at Hachioji so Tonbei gets the blame. Still disguised as Tonbei he gets close to Shintaro with the intention of stealing the map. However, Tonbei penetrates his disguise and the two duel. Genki is killed."

"Oboro, Kotaro's younger sister, pursues Shintaro and his party from Hachioji and steals Tonbei's water flask. Tonbei goes into the mountains to search for water where Taroza the Toad is waiting for him. Using Tonbei as bait, he lures Shintaro to him and deliberately allows himself to be cut down by Shintaro. When one of his branch of the Fuma ninja is killed with a sword, that sword no longer has an edge and is useless to the wielder. Kotaro attacks Shintaro who finds his sword no longer cuts. In the duel, he drops the map which Kotaro retrieves. Shintaro falls down the side of the mountain."

"Fuma Kotaro and Oboro begin the search for the Wind Fort while Dennai the Bat starts to look for Shintaro. Shintaro collapses from a wound on a mountain road and is helped by an old man and his grand-daughter. The old man is one of the guardians who for generations have kept seekers of the buried treasure from the Wind Fort. With the old man's directions, Shintaro heads for the Wind Fort and finds the map of the Water Castle. Dennai attacks him but their fight is cut short when the old man shoots the ninja. Shintaro is safely reunited with Tonbei and Shusaku and they continue their journey to the Water Castle."

"Shintaro and his party come to the aid of a girl, Namiji, who is being attacked by assassins in the road. She tells him that she is on an important mission and must get to her home province quickly. Seeing that it would be unfortunate if she was stopped, going through the Hakone Checkpoint, Shintaro plans to take her across the mountains around the barrier. On the way, they are suddenly attacked by a group of Fuma ninja. In reality, Namiji is after both Shintaro and the map of the Water Castle as she is actually a Fuma kunoichi, Ayano, in disguise. But even a cunning kunoichi falls to Shintaro's sword."

"Kotaro, who has lost five of his 10 Fuma, visits Kokufusai who had deserted the Fuma five years before. Instead of killing him according to the Fuma code, he tells him to destroy Shintaro. He takes his daughter, Yuri, hostage as guarantee and Kokufusai agrees. At Kobotoke Pass, Shintaro happens to rescue Yuri from the Fuma. Unaware of this, Kokufusai takes Shusaku hostage and challenges Shintaro to a duel. But once he discovers Yuri is safe, both he and Shintaro realise there is no point to the duel and sheath their swords. Kotaro's plan ends in failure."

"Having left Shusaku with the nun, Koshinjo, in the convent at Odawara, to keep him out of danger, Shintaro and Tonbei set out alone. Tonbei comes up with a plan to find out the strength of the remaining five Fuma. He sends Saizo of Iga, posing as a wandering ninja, to ingratiate himself with Kotaro with a false map given to him by Shintaro. Then he lures out the Fuma, one by one, and kills them. First into his trap is Hagakure Tanba, at Ashigara, near the Water Castle."

"Having killed Tanba, Saizo reports to Tonbei that he will find out the true colours of the remaining four Fuma. But Oboro overhears his conversation. Knowing the truth, Kotaro uses Saizo to send out an invitation to Shintaro and Tonbei to come to a nearby waterfall, then sends out Oboro. Shintaro defeats Oboro and she runs away. Tonbei discovers a cave behind the waterfall. This is the Water Castle. There they find the last map, for the Fire Tower, but Kotaro, who has killed Saizo, steals half the map and runs off with it."

"The Fuma gather at their base in Odawara. They set watches on the three highways and prepare to wait for Shintaro and attack him. Gennai the Phantom, one of the 10 Fuma, in the guise of a sick man, gains admittance to the convent where Shusaku is living,. There he awaits Shintaro's visit. That night he discovers from conversation with Tonbei where the two are hiding. Immediately, he gathers his men and mounts an attack. But he falls into the trap set for Shintaro and with his dying breath sends a signal to the three remaining Fuma."

"At Odawara, samurai with connections with the Hojo family have begun secret meetings, centred around Jindai Naiki, the castle warden and chief retainer of the Okubo family, the lords of Odawara Castle. When Kotaro hears of this, he sends Kitobo to find out what these meetings are about. When he learns of the reason for the Fuma's activity, Shintaro disguises himself as the retainer and goes to Kotaro but his disguise has been penetrated and Kitobo takes the opportunity to attack the real retainer. Shintaro is in great danger but is rescued by Oboro and manages barely to save the real retainer."

"At the Sounji, the family temple of the Hojo, the ninth ninja, Kuromaru impersonates the chief priest. He gives Shintaro some tea laced with a paralysing drug. Then he takes Shusaku and the abbess Koshinjo hostage. He lures Shintaro to the ruins of Ishigaki Castle, weakened as he is by the drug. However, unknown to Kuromaru, Oboro intends to help Shintaro. Under her guidance, Tonbei rescues the two hostages and she kills her comrade, Kuromaru, for Shintaro's sake."

"The Fuma plan to revive the fortunes of the Hojo family by winning the castle warden, Jindai Naiki to their side. They have observed the ambition of the junior minister who wants Kamijiro's position. The last of the ten Fuma, Yaheiji the Typhoon, tells the junior minister that government spies have been coming and going from Jindai's mansion. If he colludes with spies, he will have to commit harakiri. But if the matter is to remain secret, he must press Jindai to support the Fuma. Shintaro hears of the Fuma's plan, kills Yaheiji and rescues the chief minister, but Kotaro steals the rest of the map.

"Shintaro and Tonbei follow the Fuma, using a trail of shuriken left by Oboro as markers. Aware of his sister's treachery, Kotaro uses a false trail of shuriken to drop Tonbei into some rapids, and then lures Shintaro, using Oboro as bait, to a small hut where he shuts him in and sets light to it. Then he heads for Hell Valley (Jigoku-dani). Searching for the Fire Tower, he encounters Shintaro and Tonbei whom he thought dead. Even though badly wounded by Shintaro, Kotaro finds the cave of the Fire Tower. By sheer strength, he blows up the cave and himself and is buried together with the gold."