Koji Kashin

is an "Inner" from the organisation Kara that's in charge of the sector on the outskirts of the Land of Fire.

Personality
Koji is a enigmatic man, as well as a straightforward and no-nonsense individual. While seemingly loyal to Kara, he apparently operates under his own views as he was willing to assassinate a fellow colleague. He also appears to have an interest in Boruto Uzumaki. Self-centred as he may appear, he has consistently shown himself to be a very rational and perceptive man. He is very calculating and methodical in his approach, able to immediately determine the truth of the situation before him and likewise able to determine how things will most likely play out. He is also shown to very persuasive, able to convince the very stubborn and loyal member of Kara to follow his play.

Appearance
Koji is a tall man with long white hair which he keeps in a topknot, allowing some to fall to his shoulders, along with a trimmed beard along his jawline. He also noticeably wears a mask which conceals the top-half of his face, along with the black hooded robe with maroon lining that seems standard of Kara. Red markings can be seen at the corner of his eyes, extending downward and ending at some point beneath his mask. Beneath his robes, during his meetings with Kara and Ao, he wore a long maroon coat with a row of buttons on the right side; during the meeting with Kara it was left unbuttoned, but while meeting with Ao the buttons were fastened and he wore a belt over it. Later, when confronting Team Konohamaru, he donned a shorter maroon jacket with black lining and straps with buckles, as well as a brown tactical belt and armour on his upper right leg and a pouch on his left hip.

Abilities
Koji is noted to not be an ordinary person, and regards himself as an assassin. Against Konohamaru Sarutobi, he bluntly considered the jōnin as far too inexperienced to confront him. He quickly outmanoeuvred Konohamaru and would have killed him with his techniques if not for Boruto's Kāma. Jigen, the leader of Kara, openly acknowledged Koji as being a very capable man.

Physical Prowess
He showed noticeable stealth skill, being able to sneak up on the experienced elder in his team unnoticed, albeit he did suggest that he was losing his edge in old age. He is also very proficient in taijutsu, able to skilfully dodge and parry all of Konohamaru's attacks.

Ninjutsu
Koji uses ninjutsu from Konohagakure, such as toad summoning and the Rasengan. With the jutsu, he can perform the Summoning: Boiler Toad technique to crush a human, and using the Rasengan, he can match Konohamaru's own technique. Koji can utilise Fire Release in the form of True Fire of Samadhi, that spontaneous combust an individual, which is strong enough to overcome a target's regeneration capabilities and never extinguish. He can also use fūinjutsu to paralyse targets within his erected pillars.

Versus Momoshiki Arc
In the anime, during the days leading up to the Chūnin Exams, Koji seemingly attacked a disgruntled Katasuke Tōno in his Konohagakure lab, as part of a conspiracy with Ao to place the man under a mind-controlling genjutsu in order to extract intel for Kara. Having learned that Momoshiki Ōtsutsuki was defeated, he assumed Naruto Uzumaki was the person responsible.

Ao Arc
Upon their organisation losing their vessel, Koji discusses the matter with the other members of Kara. Immediately after their meeting, Koji approaches the elderly man of their group to assassinate, and mocks him for not noticing his presence. After impaling him with a kunai, Koji incinerates the man, before thinking about Konoha. Shortly later, he approached Ao on the Thunder Train, and instructed him to retrieve the vessel Kara lost, and provided him with the weaponry for the mission. After Ao fought Team Konohamaru during his search, Koji approached him, and questioned Ao's resolve to fight fellow shinobi again. Stating his compassion has long since gone, Koji was content with his answer and warned him about their enemy preparing an ambush for him before departing.

Having watched Boruto defeat Ao, Koji summoned a toad on top of the pair, which crushed Ao to death. Refusing to enlighten them about Kara, he paralysed the team using fūinjutsu. Overcoming the technique, Konohamaru Sarutobi faced Koji alone, during which he attempted to strike Koji with his Rasengan, prompting Koji to counter it with his own. Complementing his opponent on his skill, Koji engulfed Konohamaru in flames, which triggered Boruto's Kāma activating. Shocked to see it, Boruto subconsciously absorbed Koji's techniques. Thanking Boruto for showing him it, Koji decided to leave, before complimenting Mitsuki for stopping Sarada Uchiha from recklessly pursuing him.

Kawaki Arc
Shortly after, Koji observed Team Konohamaru making contact with Kawaki, before being joined by Delta. Realising she didn't have faith in him recovering the vessel, Delta informed him that she invited Garō to partake in the mission. When Boruto revealed his Kāma to Kawaki, Koji questioned what would happen next.

After Kawaki killed Garō and fainted from overheating, Koji convinced Delta against getting rid of the Konoha-nin and retrieve Kawaki then and there, feeling that Boruto having a Kāma merited further observation before taking action, also arguing that the crash blimp made it inevitable that the world would learn about Kara before bowing to their power.

Trivia

 * Koji Kashin shares his name with a folkloric magician believed to have lived in the late Muromachi period, though his historicity is debated. He is often depicted as a white-haired, bearded, elderly man in robes, and is said to have used his illusions to deceive and defraud prominent rulers such as Oda Nobunaga.
 * He shares many abilities with Jiraya (Ability to use the rasengan, summon toads, use fire release)