A barrier (結界, けっかい, "Kekkai") is a membrane of either spiritual or demonic energy, protecting the one who erected it from all sorts of dangers; such as physical intrusions or merely concealing one's presence. While barriers are protective in nature, they can be used for offensive purposes as well. Barriers can be cast over a wide area, as with Mount Hakurei, around an individual, or en masse. The strength of a barrier depends on the owner's spiritual or demonic power. Less powerful barriers can be broken into by throwing another barrier of the same or greater power against it. Barriers can be broken through other powerful mean's of attack as well (e.g. sacred arrows).
Throughout the series
See also: Midoriko's cave
Midoriko's cave has a power of the barrier as Inuyasha and his friends can go through except for Myōga as Miroku knows the Naohi, the good spirit of the Shikon no Tama which means "4 Souls" that the 4 souls called: Aramitama (荒魂, "Courage, lit. Wild Soul"), Nigimitama (和魂, "Friendship, lit. Harmonious Soul"), Kushimitama (奇魂, "Wisdom, lit. Wondrous Soul") and Sakimitama (幸魂, "Love, lit. Fortunate Soul"). Later, Myōga rides on Kirara to let her to go through the barrier. Kikyō's Shinidamachū can go through the barrier of her cave.
See also: Naraku's barrier
Naraku, over the course of the series, made use of three different types of barriers, allowing him to either conceal his presence or shield against physical onslaughts. Even some of his incarnations (i.e. the Infant, Hakudōshi and Byakuya) were able to erect barriers. The other barrier of his evil aura where Mount Hakurei is causes Kikyō's Shinidamachū to prevent from bringing her souls.
Kikyō can focus her spiritual power into extremely durable energy shields or screens. Under a barrier, she creates areas that neither humans nor demons can break into. When a human makes a barrier, even an ascetic monk must concentrate hard, but in Kikyō's case, she can maintain a barrier in her sleep. When Kikyō have Midoriko's soul, it causes to make her barrier stronger and even Kagome can't go through.
Hakushin was a high-level Buddhist priest and living Buddha who created the barrier around Mount Hakurei. His barrier hindered even Sesshōmaru, a very powerful daiyōkai, and was able to cancel out the demonic powers of the yōkai sword, Tōkijin, and the protective properties of the Robe of the Fire-Rat; even the poison Miroku takes in from the saimyōshō was purified, saving him from certain death. The barrier's purification abilities were so great that it forces Inuyasha into his human form as a result of the suppression of his yōkai blood.
Blood Coral Crystal
See also: Blood Coral Crystal
The Blood Coral Crystal, is a red orb and a precious heirloom passed down to each guardian of the Hyakki Mori clan barrier, it gives them the ability to put up a powerful barrier and it stores all the power of each generation of guardians like Shiori's grandfather Taigokumaru and her father Tsukuyomaru.
See also: Time Barrier
The Time Barrier, is a spiritual shield that renders the ability to freeze time ineffective on those touched by it.
See also: Rainbow Pearl
Shiori has the ability to create a protective barrier over an area to prevent any pure-blooded demon from entering even without the Blood Coral Crystal which is her family heirloom from her paternal side.
See also: Mount Musubi Mount Musubi has put up a barrier by Kirinmaru as Bokusenō said, and when Towa and Moroha approached the mountain, they were warned by Setsuna that it's has cloaked barrier. As those three entering the mountain, Towa and Setsuna didn't get pass through the barrier expect for Moroha. Since she pass it where she met Kirinmaru's daughter Rion. After she became a doll, she uses the Kyūyōkon Root to dismantle the barrier around the mountain as "Kirinmaru, begone from here!" that would create the Hoshikiri no Fue and will lead to unleash the Demon Spirit Beast.
- The colors of the barriers seem to be violet for evil characters, and blue for good characters. It doesn't seem to be based on demonic or spiritual energy, as Tessaiga's barrier is blue and Naraku, Hakudōshi, the Infant and Byakuya's are violet.
- InuYasha anime; Episode 167
- Zusetsutaizan Ōgikaiden, page 143
- InuYasha anime; Episode 26
- InuYasha The Final Act anime; Episode 2
- InuYasha anime; Episode 109
- InuYasha anime; Episode 22
- InuYasha anime; Episode 23
- InuYasha The Final Act anime; Episode 2
- InuYasha anime; Episode 118
- InuYasha anime; Episode 74
- InuYasha anime; Episode 77
- InuYasha anime; Episode 112
- InuYasha the Movie 2: The Castle Beyond the Looking Glass
- InuYasha the Movie 4: Fire on the Mystic Island
- InuYasha the Movie 3: Swords of an Honorable Ruler
- Hanyō no Yashahime: Episode 12
- Hanyō no Yashahime: Episode 8
- Hanyō no Yashahime: Episode 16
- Hanyō no Yashahime: Episode 20
- Hanyō no Yashahime: Episode 24
- Hanyō no Yashahime: Episode 27
- Hanyō no Yashahime: Episode 28
- Hanyō no Yashahime: Episode 29