Dimension Manipulation is an expert-level aspect of the Hazama-Ryu Kekkaijutsu. Experienced Kekkaishi are typically able to manipulate dimensions to some extent. This includes the creation, use, and maintenance of portals, as well as the navigation through, and repair of, damaged dimensions on the verge of collapse. Because of its high degree of difficulty and potentially grave consequences, dimension manipulation is usually taught to younger Kekkaishi by their elders while under close supervision.
Handling portals appears to be the most basic type of dimension manipulation. According to Shigemori Sumimura, a portal created by a Kekkaishi is an entity in itself. Requirements for portal creation vary, depending on the desired size of the portal, as well as the creator's skill, power, and condition. For example, Tokiko Yukimura apparently had the instinctive ability to create small time-space distortions as a young girl, though she was only able to do so after using too much power, which caused her to go into an uncontrollable rampage. However, nearly every other time a portal is created, talismans are set up beforehand to simplify the process, and the number used generally reflects the size and difficulty of the portal.
Once created, a portal typically must be maintained in order to stay functional. This involves providing it with a constant source of power and stabilization, such as an additional Kekkaishi (assuming the creator cannot do so for some reason), or even a Shikigami clone of a Kekkaishi.
Kekkaishi are among the few types of ability users able to create and recreate space. As a result, they are almost always called upon when a Shinyuuchi is badly damaged and in dire need of repair.
In most cases, the damage to a Shinyuuchi takes the form of a black, gaping hole in the landscape. The Kekkaishi's task, then, is straightforward, yet complicated: the hole must be closed up, but this is more difficult than it sounds. In a process that resembles sewing, the Kekkaishi must create a net with Nenshi around the edges of the hole. Next, once the entire hole is covered, they must tighten the net by circulating power around and into a single point. Finally, any remaining spaces must be filled in to complete the process. To better accomplish this, the Kekkaishi usually places a Kekkai just above the center of the hole to provide them with the best possible view, and uses a large number of paper charms to support their work.
In cases of extreme damage, however, this process alone may not be sufficient, as excess power may erupt from the hole, making it nearly impossible to secure the net for very long. In these cases, a Kekkaishi must actually enter the damaged dimension, seek out any additional holes, and repair them before fixing the central hole. This is extremely dangerous, because virtually anything remaining within a dimension when it collapses is destroyed. To protect against the environment, a Kekkaishi surrounds them self with a thin Kekkai that guards the body.
Even if caught within a dimension during a collapse, a Kekkaishi may be able to survive and escape. A portal or pathway created by a Kekkaishi may provide some protection against collapse, as with sufficient power, a Kekkaishi may be able to temporarily brace the pathway, delaying the damaging impact of the collapse for a short time. In addition, a Kekkaishi that is proficient with Zekkai may use it to survive a collapse and eventually make their way out of the dimension.