Chōmei

, more commonly known as the, is one of the nine tailed beasts. It was last sealed within Fū from Takigakure.

Background
Chōmei and the tailed beasts first came into being in the waning days of Hagoromo Ōtsutsuki, who used his Creation of All Things Technique to divide the Ten-Tails' chakra into nine separate bodies and giving each a name. Some time after being created, the Sage explained to the young tailed beasts that a link existed between them despite their separation. He also foretold of a day when they would be brought together again - though not as they were - and that at that time someone would emerge to show them what true power is. After Hagoromo's death, the tailed beasts drifted apart, apparently due to Kurama's belief that their number of tails was an indication of their strength. Chōmei eventually fell into the possession of Takigakure and was sealed into Fū.

In the anime, during a joint Chūnin Exams between Konohagakure and Sunagakure, Fū attempted to stop the Suna-nin Hōichi from extracting Shukaku from its host Gaara. Her failed attempt caused her to draw the attention of Hōichi, who also began extracting Chōmei from Fū. Ultimately, the extraction was stopped by the intervention of Neji Hyūga, who used his Gentle Fist to block the chakra points from which Chōmei was being extracted, thereby repelling the chains. Fū was later captured by Akatsuki members Kakuzu and Hidan, leading to Chōmei being extracted from its jinchūriki and sealed within the Demonic Statue of the Outer Path.

Personality
Chōmei seems to have a happy, go-lucky personality — which it seemingly shares with its jinchūriki as shown when it introduced itself to Naruto, referring to itself as, which might be an allusion to the fact that it has seven tails and the number seven having long been seen as a lucky as well as happy number. It also had a habit of using the word lucky in conversation, reflecting its personality.

Appearance
Chōmei resembles a blue, armoured, with six of its seven tails resembling green insect wings, along with an actual seventh tail, all growing from the end of its abdomen. The stem of the tail is green but the wings are orange. Its eyes seem to be covered by a helmet-like skull, from inside of which, an orange glow can be seen. It also has spike protrusions on its shoulders and a row of slits on each shoulder, and six legs — three on each side. The legs are also covered by the blue armour, with the exception of extreme ends which are green in colour. It has two pincers with three parts on its face, covering a mouth full of sharp teeth. On its back behind its head, it has a large two sectioned horned protrusion. During the last remaining days of the Sage of the Six Paths, Chōmei was just in its larval stage of development but still had its tails.

Abilities
As a tailed beast, Chōmei possesses massive amounts of chakra that it can share with others and can use the Tailed Beast Ball. Using its wings, it can emit blinding powder and  has the ability to fly. It also utilizes insect-based attacks, such as biting or ramming its horn into the enemy. It can also create Chakra Threads for a Cocoon which blocks Chakra Absorption Techniques. It has immense durability, able to withstand being slammed into the ground by Kurama.

Fourth Shinobi World War: Climax
After Son Gokū was resealed into the Demonic Statue of the Outer Path, Tobi, who was intent on going all-out from that point on, forced Fū to fully transform into the Seven-Tails. The opposing tailed beasts prepared to attack the shinobi, but they were rebuffed by a fully-transformed Naruto. After the Seven-Tails was grabbed mid-flight and sent plummeting to the ground by Naruto and Kurama, the opposing beasts regrouped and then prepared a collaborative Tailed Beast Ball, which was met by one from Naruto and Kurama.

As Naruto entered a deeper plane of the tailed beasts' consciousness, Chōmei introduced itself to the young shinobi. Later, as Chōmei was freed from the chakra receiver, it affirmed Kurama's belief that Naruto was the person the Sage of the Six Paths had spoken about so long ago before being resealed into the Demonic Statue of the Outer Path.

Birth of the Ten-Tails' Jinchūriki
Chōmei appeared alongside the other tailed beasts with the exception of Gyūki and Shukaku when the Ten-Tails looked down at Naruto. The image of the tailed beasts, along with a silhouette of the Sage of the Six Paths, drove the Ten-Tails to a fit as it evolved further. Later, Chōmei is pulled out of Obito through the combined teamwork of the Allied Shinobi Forces, thus freeing it, alongside with the other imprisoned tailed beasts.

When Madara ran towards the tailed beasts, both Shukaku and Gaara conjured numerous sand bullets and were able to restrain the Uchiha's movements. Using the opportunity to attack, the tailed beasts each took a swing at their opponent, giving sand-manipulating duo an opening to use their Desert Layered Imperial Funeral Seal, but Madara managed to escape the sand pyramid with his Susanoo. As Naruto in Tailed Beast Mode pinned Madara down with a tail, Chōmei and the other tailed beasts joined in and did the same to increase the damage, but the Uchiha survived their attacks and retreated to a safe distance. After he received his own right Rinnegan eye from a White Zetsu clone, Madara quickly summoned the Demonic Statue of the Outer Path from Obito's body, and used the Rinnegan to repel the tailed beasts. With the tailed beasts stunned, Madara then chained them up and sealed them back into the Demonic Statue.

Later, the chakra Chōmei transferred to Naruto earlier, manifested within Naruto's subconscious along with the other tailed beasts to speak with the young jinchūriki and the spirit of Hagoromo Ōtsutsuki. There, they all voiced their shared belief to the Sage that Naruto was the child of prophecy.

Kaguya Ōtsutsuki Strikes
After Madara's ambitions were cut short by Black Zetsu, who revealed to be the silent manipulator of shinobi history since it was first created by Kaguya Ōtsutsuki, the black entity used Madara's body as a medium to resurrect its creator. During the battle against the tyrannical princess, Chōmei and the other tailed beasts continued to support Naruto by giving him their combined power to overwhelm her. Ultimately, Kaguya was defeated by Naruto and Sasuke, who used the Six Paths — Chibaku Tensei to eject all the tailed beasts from her and seal her away inside a newly-created moon within her own dimension.

After the spirits of Hagoromo and the past Kage summoned both the tailed beasts and Team 7 back to the real world, the tailed beasts began to discuss their plans for the future since they were finally free. Sasuke, however, made his own intentions known: removing as many people as possible who could get in the way of his plans of leading the world through a revolution to do away with current shinobi systems, including killing all the current Kage and tailed beasts. Just as Sasuke swiftly subdued the tailed beasts with his Rinnegan and sealed them within his Chibaku Tensei, Naruto reassured the tailed beasts that he would save them once again. After Naruto was able to defeat and reform Sasuke, the two dispelled the Infinite Tsukuyomi and Sasuke released Chōmei, along with the other tailed beasts, from their prisons.

Video Games
Although Chōmei itself is not playable, Fū takes on its form as her awakening in Naruto Shippūden: Ultimate Ninja Storm 3 and Naruto Shippūden: Ultimate Ninja Storm Revolution.

Trivia

 * literally means "Principal Brightness" or "Principal Vidya".
 * Chōmei is the only tailed beast to have permanently undergone a complete change in appearance, evolving from a larval stage at its creation into a more insect-like, adult form.