Kinshiki Ōtsutsuki

was a member of the Ōtsutsuki clan's main family, who served as a vassal for his foster son Momoshiki.

Background
At some point, Kinshiki consumed his guardian's chakra after they entrusted him with their power.

Personality
Kinshiki was very loyal and subservient to his foster son Momoshiki, to the extent that he offered himself to be changed into a chakra pill without hesitation. He also referred to his foster son using the honourific "-sama". Kinshiki also showed a vengeful side, as he was determined to kill Sasuke Uchiha for cutting his horn off from their first battle. He has no regard for anyone other than Momoshiki; this is seen when he tried to kill Sasuke as he was trying to get his daughter to safety in the middle of the chaos Momoshiki and Kinshiki brought upon their arrival to Konoha.

As a result of his extreme power, Kinshiki was very noble and self-esteemed, traits Momoshiki also came to acquire. He is also adherent to his clan's tradition of gaining power through self-sacrifice, as he previously consumed his guardian's chakra and then offering himself to Momoshiki in turn.

Appearance
Kinshiki had pale skin with short spiky blue-greyish hair, a full beard, and a long horn above his left eye that was later stubbed by Sasuke Uchiha. He had big hands and a burly physique accompanied with a towering height that reached over two metres.

He wore a pale blue shirt with back cuffs and a high collar over which he wore another darker appendage with a grey sash wrapped around his waist. He also wore grey pants and black, flat shoes on his feet which were upturned at the toes.

Abilities
Kinshiki was an extraordinarily powerful being who, alongside Momoshiki (and in the anime Urashiki), was deemed a threat greater than Kaguya. He was capable of restraining a perfect jinchūriki, holding his own against multiple Kage-level opponents at the same time and stalemating Sasuke Uchiha.

Ninjutsu
Kinshiki possessed the ability to absorb any kind of ninjutsu and transform the chakra into various red glowing ninja tools at will, which he was proficient with handling. He could also fly and sense chakra, being able to locate fragments of Kaguya across countries. In the anime, Kinshiki was capable of using Space–Time Ninjutsu to transport himself to a destination. He was also able to cloak himself in purple electricity.

Physical Prowess
Kinshiki possessed incredible strength and durability, as he could escape being confined and immobilised by two Kage. Sasuke attributed he was strengthening his muscles with some kind of technique. Despite being on the verge of death, he could cut down a God Tree with a single slash of his halberd. Kinshiki was proficient in close-range combat and showed deceptive speed, being able to fight on par with Sasuke.

Byakugan
Kinshiki possessed the Byakugan, granting him telescopic vision, x-ray vision, a near 360° field of visual perception (with the presumed exception of a small blind spot at the upper thoracic vertebrae), and the ability to see the chakra pathway system and its tenketsu.

Academy Entrance Arc
In the anime, after investigating Kaguya's world, he reported to Momoshiki on an unidentified planet. He stated that he had observed substantial tears and that its space curvature had exceeded 16, an abnormality that she should have reported to their clan. Wondering whether Kaguya had betrayed the clan or been destroyed by her world's inhabitants, Momoshiki ordered him to prepare to depart.

Versus Momoshiki Arc
Kinshiki and Momoshiki encountered Sasuke, who had been travelling through another dimension to gather information on a threat greater than Kaguya. In a blizzard of another dimension, Kinshiki engaged in battle with his kanabō against Sasuke and his sword, battling Sasuke to a standstill despite Sasuke managing to cut off one of his horns. Sasuke eventually escaped after seeing Momoshiki and realising he couldn't take on both of them at once despite Kinshiki's attempts to stop him. Later, Momoshiki used his pills to transport the pair to Earth, where they begin searching for fragments of Kaguya's chakra. Their search lead them to Killer B, where they immobilised and defeated him. Afterwards, Momoshiki's absorbed his chakra, as Kinshiki reports that there is a greater source of chakra in the east, before departing there.

They appeared during the Chūnin Exams in Konohagakure and started creating chaos. Kinshiki destroyed the arena and attempted to attack Sasuke and his daughter. Shikamaru Nara uses his Shadow Sewing Technique to restrain Kinshiki and Momoshiki, but Momoshiki absorbs his power. After Momoshiki explained their goal to gather Kaguya's scattered chakra and cultivate it into a new 'cinnabar panacea' in order to gain eternal youth and supernatural powers, Kinshiki fought Naruto and Sasuke, who combined Kurama and Susanoo to shield themselves. However, Kinshiki and Momoshiki successfully captured Naruto Uzumaki when he allowed himself to be caught in their technique to protect his son, Sasuke, and Sarada.

They took Naruto to another dimension and bound him to begin the ritual of extracting Kurama from him, but the process proved to be too slow; Sasuke, Boruto, and the four other Kage arrived to rescue him. Kinshiki fought against the other Kage and was initially captured by them, but broke free from their techniques. He then unleashed a powerful blast around them, causing massive destruction and severe injury to himself. To everyone's horror, Momoshiki turned Kinshiki into a chakra pill and devoured him to increase his strength.

Trivia

 * Masashi Kishimoto's character sketch of Kinshiki shows him with normal-sized hands.
 * Like his cohorts Momoshiki and Urashiki, Kinshiki was named after a Japanese folk hero whose name includes "Tarō", in this case the legendary warrior Kintarō. His gigantic form and stern demeanour were also adapted from the folktale.
 * Kinshiki's attire and abilities also draw inspiration from the folkloric warrior monk Benkei, a retainer of Minamoto no Yoshitsune, who likewise inspired Momoshiki's design. According to folklore, Benkei sacrificed his life to protect Yoshitsune from his enemies while he commited seppuku, dying from countless wounds while standing upright. This is mirrored in Kinshiki's final sacrifice to grant Momoshiki more power.