Kuusetsu

At first, Kuusetsu appeared as a large egg with two legs and wings.

[Spoiler] After absorbing Koko Zenibako and Naon Yuno, Kuusetsu took on the physical traits of a Humanoid Shuuki, their traits, in particular, including a number of small horns around her head resembling a crown. Aside from her appearance, Kuusetsu also took on the personality traits of Koko and Naon, being highly confident both in her strength and beauty. [/Spoiler]

She wears a white kimono that has long sleeves and gloves wrapped around her two middle fingers. She also has a series of dots below each eye, which seem to indicate the number of people she has absorbed. After absorbing Mira Kamiunten, she gains four dark zigzag streaks in her hair.

When in her powered up form, Kuusetsu's hair becomes longer and more unkempt. Her eyes turn black and her crown of horns recedes, being replaced by two large horns on her forehead.

She is also prone to anger, to the point of even knocking down Rairen, who looked down on her, without hesitation. She is also rather cheerful whenever around Shikoku and Jouryuu, often referring to her as Shikoku-nee and Jouryuu-nee respectively. would beam whenever she has an idea.

Likely matching the fact she was just born, Kuusetsu is rather immature whenever compared to Shikoku and Jouryuu, which was noted as she went to the Human World despite being told to aware for the other Thunder Gods to be born. As such, she often acts on her desires and curious nature: it is first noted as she kidnapped multiple beautiful women to devour, and became curious about sex, wanting to have intercourse with Yuuki against his will in an attempt to understand how it felt. Kuusetsu likewise has no issue with being seen nude by others, often appearing naked in Yuuki's mind.

Despite her young age, Kuusetsu is strong-willed and loyal to the Eight Thunder Gods, choosing to not reveal any information in regards to the Eight Thunder Gods because of knowing the potential demise should Yuuki die fighting them.

[Spoiler] She's super sexually interested in Yuuki, she's even tried to have sex with him in his mind while he's sleeping and it looks like she won't stop until she gets it and even though she's inside his head she seems to have a pretty cool relationship with him when she's not trying to get him to have sex with her. She was able to convince Fukuma and Rairen to make peace with Yuuki. Despite not willing to reveal any information about the Eight Gods of Thunder to Yuuki, she did warn him not to engage with Taikyoku. As a spirit in his inner world, she tries to get Yuuki to be more comfortable around women, often appearing naked in front of him and offering to service him with her body. [/Spoiler]

Little is known about Kuusetsu's background. While in her larval egg state, Kuusetsu apparently rejected some "food" that was presented to her by her fellow Thunder Gods.

Being one of the Eight Thunder Gods, Kuusetsu is one of the eight strongest beings in Mato, considered one of the eight gods. Although, she is the youngest compared to Shikoku, Jouryuu, and Rairen, she was powerful enough to send Rairen flying backwards using a single punch.

Before maturing, as an egg, and afterwards, Kuusetsu can absorb living beings into herself using a large mouth that opens up from her body, as a means for her development and gaining nourishment. Whoever she absorbs becomes living batteries to fuel her as long as they're inside her. As such, she also inherits all their traits and superhuman abilities, taking on the physical appearance of those she absorbs. However, it isn't foolproof or necessarily permanent as those inside her with a strong enough will can resist her and use their abilities as a means of resisting against her. In the event that Kuusetsu loses all of her absorbed victims, she loses her previous nourishment, and thus reverts back into her egg form.

Kuusetsu is able to transform into a powered-up state that greatly amplifies her speed and strength. While in this state, she was powerful enough to send Rairen flying with one punch. Kuusetsu can also transform her hand into a scaled claw and charge it up with tremendous energy for a devastating attack.

Kuusetsu can detach and fire feathers from her kimono. By merely tapping her victims with them, she can render them unconscious, immobilize them, or control their actions. They are also capable of great widespread offensive damage as they were able to destroy most of Mira Kamiunten's clones with one volley. Kuusetsu is also capable of controlling them remotely.

Kuusetsu demonstrated the ability to fly in the air, stay afloat and move quickly and fight at long distance. By combining this ability with other skills that she has obtained, she can fight more effectively in the air.

Kuusetsu can produce a special droplet, the droplets of god from her saliva, whose initial effects are unknown. However, in the event that her body is destroyed, her soul can live on inside her host's "spiritual space" where her power still resides. Although she can see, interact, and communicate with her host, but is unable to interfere with them in the real world.

Using All-Killing, Kuusetsu multiplies her arms, attacking her opponent with a flurry of powerful punches.

[Spoiler] After inhabiting Yuuki Wakura's body with her God Drops Kuusetsu became able to manipulate Yuuki's dreams while he sleeps and chat with him. She also has cognizance of his memories whether he is awake or asleep, and knows what Yuuki does while he is awake. To a certain extent she can exercise part of her powers as a Thunder God, but physically and spiritually she cannot harm him, or try to escape from Yuuki's spiritual subspace, not having a physical body. (If she manages to do so somehow, or if Yuuki dies, Kuusetsu will die as well). [/Spoiler]

(Source: Mato Seihei no Slave Wiki)