Tenka Nihisaki's Jinchūriki Forms

Tenka Nihisaki is the jinchūriki of the Eight-Tails, and is therefore capable of transforming into various forms that resemble her tailed beast, until she finally takes on the complete form of the Eight-Tails. Unlike most other jinchūriki, she has full control of the Eight-Tails and her tailed forms. Prior to her abandoning of Kumogakure she was forbidden from accessing the Eight-Tails forms unless there was an emergency situation, requiring approval from the Raikage. While the jinchūriki forms were the most prominent showing of it, the Eight-Tails' power was always present in some form as Tenka could produce ink and access the Inferno Release through her Tailed Beast.

Initial Jinchūriki Form
By simply tapping into the Eight-Tails' chakra, Tenka's body begins its initial transformation. The first signs of this are her eyes' pupils become slitted, and will change from green to red. Following this, her nails and canine teeth grow longer and sharper and her dark brown hair will grow spikier and become unruly, as it stands on end, the ribbon wrapped in her hair is commonly known to come undone during the change. Tenka's Iron Armour Seal becomes visible on her left cheek, reacting to the presense of the Eight-Tails' chakra. While she can still stand on her own two feet, Tenka can move at greater speeds by manoeuvring on all fours in a manner that looks similar to the Four Legs Technique used by the Inuzuka clan. This was originally the only form Tenka could access when she did not have control of the Eight-Tailed Beast, however it was later phased out by the Version One forms after Tenka gained total mastery of her Tailed Beast.

As part of her training in Kumogakure, Tenka was taught how to contact the Eight-Tails in order to make use of its chakra. Even through the initial form is the weakest of all jinchūriki forms, it still increased Tenka's physical strength (she was capable of stopping a massive toad backed by incredible strength of its own), and its healing rate was able to regenerate her right forearm, after being incinerated by a Kumogakure ANBU's Fire Release. This form also increased her speed to such levels that nothing short of a fully matured Sharingan was able to track her movements.

Tenka was often using this form during her training due to the increased physical power and access to much larger chakra reserves that it provided. As such it increased her limits and allowed her to go much further in a shorter length of time than if she had to take longer breaks in order to recuperate and replenish herself.