Eternal Loop is one of the strongest genjutsu in existence, which affects targets through physical sensations shared between them and the user.In exchange for the temporary ability that it grants the user it eats away a huge amount of chakra.
To begin the technique, after selecting any arbitrary moment, the user through their eyes (Hakkaima in Takumi's case) to remember the physical sensations both of their body and that of their opponent's during that instant like a photograph. The user must then intentionally replicate the same sensation and in the same way, memorise that instant with their eyes . The Eternal Loop overlaps and connects these two identical bodily sensations, as well as the flow of time between them, creating an infinite loop of events that entraps the opponent's consciousness.
Whilst under the effects of the technique, the target stands motionlessly as the loop of events continually replays inside their mind.Each time a loop is repeated, any physical damage incurred is reset as it were before the start of the loop, although the remains of severed appendages do not disappear. Despite being able to become consciously aware of their situation and act differently, the victim is unable to significantly alter or escape from the inevitable progression of these events.Assimilating them into itself. This not only breaks the opponent's will but also deals a huge amount of Physiological damage once the technique is utilized it leaves the victim unstable both physcially and mentally as he is left incapacitated also his chakra path is completely blocked.One may add space-time abilities with it hence freely manipulating the time period or space where the technique has to take place making it more effective.
However when casted on the user himself caster removes the boundaries between reality and illusion within their personal space. To a degree this allows the user to control their own state of existence,hence creating an Infinite loop of repeated illusions, which makes the user Immortal to certain degrees.While the user remains physically real while fighting, this technique is capable of turning any occurrence including injuries and even death inflicted upon themselves while the technique is active into mere "illusions".
It can be also utilized in a different manner by exposing owns chakra and instill great fear into those that feel its presence,with this he can paralyze an opponent just by focusing pressure through their stare or presence.As they are stresses ,instilled with fear and paralyze which itself keeps on repeating,too much usage of this technique can cause the death of the victim and sometimes the user himself, which is why this technique has been labelled as a Kinjutsu.