Kankitsu Akitsuki

is Remon Yoimura's distant relative and fiancé.

Background
When they were little, Kankitsu and Remon grew up together. Sometime later, when Kankitsu reached the age of twenty, a curse mark appeared on his right palm. In order to subdue the curse for another hundred years, Kankitsu was ultimately betrothed to Remon. When he visited the Yoimura household to discuss the date for the wedding ritual, Kankitsu was lured and tricked by Sōma to touch its rock, where the demon possessed him into doing their bidding. This made him become cold toward Remon.

Personality
It was noted that originally, Kankitsu was a very considerate and cheerful person, smiling when playing with Remon. Later while possessed by Sōma, his positive nature was replaced by a cold and detached one. Taking a very authoritative attitude, he carried himself with the view of always knowing what is right.

After Kankitsu was freed from Sōma's influence, Kankitsu returned to his original self.

Appearance
Kankitsu has red shaggy hair and beige eyes with black pupils and a pale complexion. He wears a black business suit with a grey collared dress shirt and a light violet necktie. When he was manipulated by Sōma, his eyes were blank and pupilless.

Abilities
While possessed by Sōma, Kankitsu was able to produce a white aura with which he could steal one's memories upon physical contact. Alternatively, he could unleash his energy as blasts to steal people's memories from afar.

Konohamaru Arc
When he and Remon were continuing to prepare the wedding ritual, they were approached by Konohamaru Sarutobi and Boruto Uzumaki who previously befriended Remon in Konohagakure with the goal of returning her handkerchief. With hollow politeness, asked them to leave. Later, he had Remon confined to a small room, insisting that it was for her protection, and took her special hair clip. When he noticed that Asaki was growing suspicious of him, he approached her and wiped her memories. Later, he went to the sacred shrine that housed Sōma. Inside, he smirked at how things were going smoothly for his plans. He then prepared to destroy Remon's hair clip, but was stopped by Asaki, who knew the significance the ornament. Realising that handmaiden was a liability even without her recent memories, he decided to take care of her completely, manifesting the power of Sōma. Before he could act, Boruto appeared to defend her. Despite the genin's efforts, Kankitsu erased both their memories. However, Boruto, who had the hair clip at hand, retained consciousness and escaped the now-mysterious places. Kankitsu decided not to follow him as the hair clip was taking with the boy and thereby removed as a problem. Later, he told Remon they would move the wedding ritual to the following day.

When the ritual began, Kankitsu took his sword that was meant to sever a growing horn to instead destroy the entire seal. Now no longer having use of him, Sōma severed its control from Kankitsu. Upon awakening, he was horrified to realise what he had done. Against his wishes, Remon aided Konohamaru and Boruto in defeated Sōma once and for all by sealing it inside her, costing Remon her memories. Despite this, Kankitsu was committed to restart their relationship with each other by helping her remember as much as possible.

Trivia

 * "Akitsuki" (明月) can mean "bright moon" or "harvest moon", while depending on how it's written, "Kankitsu" can mean the following:
 * Written as 姦譎, it means "wickedness", "iniquity", "dishonesty"
 * Written as 柑橘, it means "citrus (fruit)", much like Remon's name being a pronunciation of "lemon"