Arima has an appearance of a young man. He is a tall man who wears glasses and has long white colored hair with blue ends. His eyes seem to be amber colored. He is mostly seen grinning. He is first seen wearing only underwear during his first appearance, which is why Rokuro always calls him "Perverted Underwear Man".
Arima is a cheerful guy who seems to like having fun. A running gag in the series; he often gets in trouble, resulting in him running away from troublemakers. Despite this, he is actually a serious person, although in a sarcastic manner. He is also displayed as a kind and caring person, this was shown when he was genuinely worried about his 'henchmen', Rokuro and Benio. He is also stated as 'a perverted underwear man bastard' by Rokuro.
However, when it comes to his son Arimori, Arima displayed a more serious tone to him speaking him to bluntly about his lack of talent as well threatening to disown him from the family when he joined the Enmado House.
Arima's true nature was found by some of the Twelve Guardians like his acquaintances since youth, Seigen Amawaka and Arata Inanaki, and later other ones like Shimon Ikaruga - by fair means or foul, the only thing he wanted is the victory to the impurities. Even his son and himself, are less important to ones who are critical to the plan, the two chosen ones cursed with special power. As a result of that, Arima is also adept at manipulating others to reach the goal.
Arima likes to flirt with women, but he also has true feelings to his deceased wife Mana.
Arima is also somewhat narcissistic, as he makes the Christmas of the Tsuchimikado Island his own birthday party.
When Rokuro started to undergo a transformation during his fight with Yuto, he was suddenly engulfed in a light and lost consciousness, just as Arima appeared through a gate greeting Yuto. Which means, he faked his death. Arima confirmed that he survived and used a spell to bind Yuto. Yuto broke free relatively easily, though it was really a diversion for Arima to use a spell to remove the barrier Yuto placed around Benio. Then, Arima took Rokuro and Benio through the gate he used to appear, to escape to the real world.
Powers and Abilities
Originally, Arima shows no indication of any actual fighting strength. However, his abilities are befitting of his status as the Exorcist's head. During the conflict between the two basara, he disposes of a huge amount of impurities effortlessly, protecting Mayura and Benio. Despite the fact that he came with 2 of the 12 Commanders, he went to Magano alone, as the commanders deemed that they'd just get in the way, a testament to the full extent of his abilities. It is implied that he may have power and skill greater or equal to the Kijin and Toda.
He was shown to be exorcising impurities without doing anything and using shikigami to track down Kuranashi, a very elusive Basara. Arima seems to specialize in Ice and Fire techniques and has very immense spell power to the point where he almost defeated Kuranashi with one blow, leaving a gargantuan crater in it's aftermath. He was presumed to be dead when Kuranashi buried him under the ground with a Seiman.
- Barrier Release (結界解放 Kekkai Kaihō?): By preparing beforehand an array of charms, Arima can neutralize any barrier, no matter how resilient, using the Five Elements principle to do it.
- Pursuit of Ages Ritual (
時律利不府之義Tokitsurifunogi?): Arima triggers this ritual during his battle against Kuranashi, that involves temporarily separating his soul from his body in a life-and-death situation to be able to revisit past events. Arima uses it to learn about what Abe no Seimei did.
"The darker the darkness is, the brighter the stars shine."