Onmyô taisenki

Riku and Souma head for the Chi-ryuu base, the main building of Mikazuchi Products. Along the way, Souma gives Riku some backrgound information on Mikazuchi, the Head of the Chi-ryuu. He has made a great impact on Japan with his projects and mergers. Mikazuchi is also an expert Toujinshi, and it is said that he uses the power his Shikigami to control his "luck" in the market. When they enter the building, Souma is left behind while Riku heads up to see Mikazuchi. Riku meets him and asks what was the crime that the Ten-ryuu committed a thousand years ago. Mikazuchi explains that the Ten-ryuu were not guarding the seal of the Fukumaden. Instead, they were taking provisions and resources from the Fukumaden. Thus, the Chi-ryuu had suffered many casualties from the Youkai that were coming out of the unguarded seal. So, the Chi-ryuu attacked the main Ten-ryuu base. Then, Riku and Kogenta fight Yuuma and Rangetsu once more atop of the building.

Kogenta is dead, and Riku has lost all of his memories from when he was a Ten-ryuu Toujinshi. So, he doesn't remember Souma, Nazuna, or the boat club. Masaomi discovers that Riku's contract with Kogenta has not been cut. But, Riku seems to be rejecting his contract for some reason. To get Riku to accept his contract and restore his memories, not only will Kogenta have to be revived, but Riku will also have to walk down a difficult path, one that will reveal his ancient past.

Riku and Kogenta arrive in a tranquil part of the Fukumaden. Riku feels very nostalgic about this place. But a Chi-ryuu Toujinshi, Gaitatsu and his Shikigami, Aogane no Nanaya, come and decide to destroy the place in search of the Toujin stone.

Oosumi, the Technology Research Department Chief for the Chi-ryuu, speaks of putting a Toujin stone into a Shikigami. When the revenge-driven Izou hears about this, he takes the Toujin stone he got from a while back into Fukumaden with him. Riku, Souma, and Nazuna head into a rocky mountain field of Fukumaden in search of more Toujin stones. Riku gets seperated from the group, and he is soon confronted by Izou. They summon their Shikigami and do battle. Kogenta easily handles Fuji, but when Izou embeds his Toujin stone into his Shikigami, Fuji then transforms into his Daikoujin form and starts beating Kogenta.

Masaomi's bike gets a flat tire. A passerby on a motorcycle helps repair his wheel. As a way of showing his thanks, Masaomi gives the man a special coupon. It is revealed later that his name is Hayate Takamiya, a Toujinshi of the Chi-ryuu.

Mozu teams up with easy-going Kikusaki (Shikigami - Houjou no Ruri) to search for more Toujin stones, and a deranged Izou goes with them, hoping to destroy Riku and Kogenta. Teru meets up with Riku and Souma. They head into a desert field of Fukumaden, where they do battle with Mozu, Kikusaki, and Izou.

Riku gets a note from his grandpa that he has left on a journey. When Riku goes to the destroyed shrine, he finds the site completely rebuilt. Nazuna tells Riku about the moon magatama and how it can allow people to enter and exit the world of Fukumaden at shrines. When Souma tells them that the Earth Style has already been in and out of Fukumaden, Riku and Nazuna take it upon themselves to go into Fukumaden. They end up in a grassy moss field. They use their Onmyou divination board to help them navigate, only to find two Earth Style Toujinshi, Kanna (Shikigami - Shuusui no Erekiteru) and Mozu (Shikigami - Hiiragi no Toubee).

While Masaomi and Kibachiyo fight Yakumo and (one of) his Shikigami, Seiryuu no Buryune, Riku and Kogenta battle Yuuma and Rangetsu. When all else fails, Riku decides to use the In that Kogenta taught him before: Hundred Ghost Obliteration Attack. But something strange happens to Kogenta after Riku uses it...

Riku's grandpa finally wakes up, and he tells Riku to go to the Ten-ryuu Taihaku Shrine in Kyoto. He eventually finds the Taihaku shrine and meets a young girl who seems to be the only person working at the shrine. She begins Riku's "training," but then a Chi-ryuu Toujinshi named Chihaya busts in and summons his Shikigami, Kaede no Kurenai. When they are about to finish off Riku and Kogenta, the girl reveals herself as Nazuna, a Toujinshi of the Ten-ryuu, and summons her Shikigami, Hiiragi no Horin.

Souma gets frustrated by Mikazuchi, his brother Yuuma, and the Ten-ryuu. So, he decides to run away, but he doesn't have any money. With no place else to go, he heads back to Riku's destroyed shrine. There, he and his Shikigami, Ikazuchi no Fusanoshin, fight Kirihito, a Chi-ryuu Toujinshi, and his Shikigami, Uzumibi no Mingobee, who have been requested by Mikazuchi to eliminate Souma.

Kogenta really wants Riku to start training, but Riku doesn't know how to go about it. Then, thanks to some of Rina's books, Riku gets some information on a special area for training. So, he, Rina, and Momo find a training area for using Toujinfu (cards for Toujin seals). Before the training could actually begin, Riku and Kogenta must fight against another Earth Style Toujinshi, Gonpachi, and his Shikigami, Souka no Raiden. The battle gets tough when Riku and Kogenta have to deal with Gonpachi and Raiden and also have to protect Momo and Rina from the demons that reside in the training area.

Following a lead from their new friend, Masaomi, Riku and Kogenta go to the mountain region of Myoureizan in search of the In for "Saikaidou Kotetsu." Along the way, Riku meets a Toujinshi of the Ten-ryuu, Teru. Because he doesn't want to get Riku involved, Teru goes off by himself. Soon after, Riku and Kogenta fight against two Chi-ryuu Toujinshi, Hazan (Shikigami - Enoki no Otochika) and Dougen (Shikigami - Tsubaki no Gorouza). Teru joins in the battle with his Shikigami, Akagane no Isoroku. Also, Riku finds out the identity of Kogenta's "partner.

The news of Yamase's disappearance has reached Chi-ryuu Toujinshi Ujiyama and Yuuma Asuka, who has just defeated a Toujinshi of the Ten-ryuu with his powerful Shikigami, Byakko no Rangetsu. Much to Ujiyama's dismay, he is told by Yuuma to investigate Yamase's leads on the Head of the Ten-ryuu. Meanwhile, as his grandpa rests in the hospital, Riku searches for clues on some old documents found in his grandpa's bedroom. However, it is not long till Ujiyama and his Shikigami, Oobi no Mumyou, confront Riku and Kogenta.