Bond of the Underworld

You Keika, who unfortunately lost his life in a traffic accident, spends his days as Tanmoku Ki's spirit shadow. Then, one day, upon realizing that he has not really received any particular training as spirit shadow, Keika tells Ki that he wishes to train. Heeding his request, Ki leaves Keika's training in the hands of In Tetsu, lord of the Tanmoku family's Mt. Ura. As Keika's training gets off to a rocky start, a mysterious youkai appears.

One day, while attending school with Ki, Keika encounters a young woman at the university who is able to see him and seems interested in being friends. She has a passion for teaching, but her lessons are not going well and she is struggling to gain the respect of her students. However, Ki suspects the woman has a very different reason for pursuing a frienship with Keika.

The young stone youkai boy mysteriously seems to have regained human form and convinces Keika that he knows the location of a young boy that Keika used to know in his youth. Seeing through the nefarious spell on the stone pendant left behind by the stone youkai, Ki destroys the pendant to break its hold on Keika. Unfortunately, this only serves to make things more strained and awkward between the two. Soon after Ki is suddenly called away to Iceland on an exorcism request.

When Keika regains consciousness, he finds himself in a hotel room with Shin Shiyou. She explains what happened and how Tanmoku Ki used her powers to save him. Upon returning home, Keika goes along with Tanmoku Ki to visit the grave of his old friend and former bodyguard, Shinryuu Shouken. There a mysterious man appears saying he wants to make Shouken's wish come true and that he isn't truly dead. Ki is shaken by this and the man opens the grave to show him the truth.

Rocked by the truth of his dearest friend's fate, Ki is overcome by nightmares that leave him unconscious and could prevent him from ever awakening again. Keika, the only one who can save him, dives into Ki's memories to try and free him from the nightmares. Silently, Keika watches from the sidelines as he relives Ki's memories from before he knew him to see just what in his past is preventing Ki from moving forward. As his bodyguard, Shinryuu Shouken spent a great deal of time with Ki, but what were his true motives?

Shouken encourages Ki to seek becoming the head of the Tanmoku family so he can fulfill his wishes; however, when Ki is promoted to the position there are many who oppose him. Ki, who doesn't want to be hated by anyone, puts on a smiling face, but since his kind nature has already been taken advantage of before, Shouken advises Ki to refrain from smiling too much for his own sake. To cheer him up, Shouken asks Ki what he really wants to do and throws his full support behind making it happen, but when Ki's desires land them in hot water Shouken's future with Ki is placed in jeopardy.

Shouken manages to save Tanmoku Ki from captivity from the former head, but the former head's son spins a story of lies to paint Shouken's actions in a bad light and gets him in trouble. The situation is further complicated when Shouken's room is searched and they find that Shouken has been hiding some of Ki's hair. With Shouken behind bars, Ki desperately refuses to believe that his trusted bodyguard and companion would betray him and helps him escape. The final piece of Ki's nightmare falls into place for Keika.

Tanmoku Ki is finally freed from his nightmare thanks to Keika, but he seems locked in a depression that he cannot shake. As the day of the ceremony dawns, Ki has no choice but to force himself to see the service through despite his ill health. But as the ceremony progresses Ki's health visibly takes a turn for the worse and Keika intercedes to help him, despite the fact that it is against the rules to do so.

Using the power of the mirror of the netherworld, Ki and Keika succeed in seeing Shouken's memories. Through his memories we learn of Shouken's history and how he came to the Tanmoku family. Ki is also able to ascertain that the reason for all of Shouken's actions while he was his bodyguard and a critical conversation between Shouken and his brother Sekijin is overheard.

Keika and Ki learn more and more about Shouken's past. Shouken has special feelings for Ki, but when he tries to explain his feelings to his brother, Sekijin, he is scolded and forced to make the ultimate choice. When Ki and Keika finally reach his memories of the day when he pointed the gun at his own head, they learn the real reason that Shouken decided to take his own life.

Sekijin and his underlings locate where Shouken has been kept hidden and steal away his body, trying to get it back to the Shouken family residence before his soul scatters and disappears. However, they are confronted by In Tetsu and the other youkai of Mount Ura giving Ki and Keika a chance to catch up. Sekijin sends Sashi on ahead with Shouken's body but she is then stalled by Tanmoku Jiun as Shouken's soul begins to scatter.

With his spiritual powers being sealed, Ki is unable to defend himself and Keika does his best to keep In Tetsu and the rest of the hypnotized youkai at bay, but Sekijin's plan seems to be succeeding. Jiun shows up just in time to help and helps turn the tide. Sekijin, in a last desperate move, tries to use his hypnosis spell on Keika but it backfires and he is surrounded by Ouyou You, Shin Shiyou, and the rest of the noble families surrounding the Tanmoku family.