- This article contains major plot spoilers from the manga that have not been revealed in the anime. Proceed at your own risk.
|Height||170 cm / 5'7"|
|Date of Birth||April 28, 1979|
|Unique Features||Bags under his eyes|
|Affiliation||Public Safety General Affairs|
|Former Occupation||F Squad Leader|
|Hometown||Sendai; Miyagi Prefecture|
|Manga Debut||Line 27; Command|
|Anime Debut||Episode 9; Command|
|Japanese VA||Akira Ishida|
|English VA||Clint Bickham|
Megumi Ishimaru (石丸 恵巳, Ishimaru Megumi?), formerly of A Squad, was appointed as the leader of F Squad in the latter half of February 2013. He infiltrated the ranks of the CCC in order to obtain enemy intel and find the book where the members of the CCC were written, in which he acted under the code name 13 (Thirteen (十三, Jū-san?)), or Jason (ジェイソン, Jeison?). His real position is within the MPD Public Safety General Affairs, the 6th Public Safety Investigation Division, Section 11. After the F Squad's disbandment, Ishimaru returned to his original position.
As a child, Ishimaru lived in a small neighborhood with his mother and grandmother. He was friends with a devil girl his age named Misaki Takenami, who was also his neighbor. With Misaki being very talented origami, it would lead with regular visits from Ishimaru and she would show off her works as well encourage Ishimaru. However, the one Ishimaru truly had his eyes on was Misaki's mother, Shizuku. However, Ishimaru's mother was not pleased with Ishimaru regularly spending time with the family, as there were some rumors going around about them having some kind of disease, being weird, and a bad influence on the children.
One night, Ishimaru snuck out from his house to the Takenami household where he saw Shizuki, for the first time, without make-up, revealing her heavy dark circles. Ishimaru asked if she was sick, but she insisted that she was fine, claiming that it was "normal" for her. All of that aside, Ishimaru was just glad she was fine. Though he was soon dragged back by his mother, Ishimaru realized at that moment that he liked Shizuku.
However, soon after, Shizuki and Misaki decided to move because the rumors had gone out of hand. As a parting gift, Ishimaru received a handmade bird-origami from Misaki. The last time he saw Shizuku was in the car, wearing protective glasses against blood.
Because of his past events and experiences, he started looking into devils through, for example, essays. This gave him a vast amount of knowledge regarding them.
Ishimaru is an adult man noted to have a spindly and weakly build, but he is actually very physically capable. He is of average height and has brown, droopy eyes and dark, heavy circles under his eyes. He has black, wavy, shoulder-length hair with middle-parted bangs that frame most of his face. He occasionally wears his hair in a ponytail.
After the 6-month timeskip, it is seen that Ishimaru sports much shorter hair which ends just above his ears. He also wears side-bangs rather than a middle-part.
Ishimaru appears to be a very apathetic, calm, and eccentric, as he often stays up all night reading manga and books, which has resulted in his sleep deprivation and the bags under his eyes. Ishimaru also used to be sly and sneak behind the others in the F Squad and listen to their plans while speaking about his own thoughts about the matter. However, he would only do this if it was necessary to plan a strategy of some sort. He also thinks that formalities are a hassle, so he'd rather people speak casually with him. He has a unique way of calling people, as he used to refer to Tsukasa Taira as "Miss Hostage", and Johannes Kleeman as "Mr. Foreigner". Ishimaru is very honest and will speak in a straightforward manner, whatever people may think. He can also say things that can be misunderstood and misinterpreted as inappropriate.Despite seeming uninterested, Ishimaru has good leadership skills and encourages the others in the squad in his own way. He wants to work with them so they can succeed in their investigation. However, he doesn't like how close-knit F Squad is or how everyone is so "soft," as he once described. At first, spending time with them made Ishimaru upset, since he has always been keen on people displaying their powers to the fullest, especially devils. Ishimaru likes devils and is very interested in them, and the thing that fascinates him the most is how devils' fundamental physical abilities surpass those of humans'. This is why he doesn't want Yuuki Anzai's talents go to waste. However, Ishimaru's fixation on Devils' strengths, and moreover, their differences with regard to humans, made him ignorant in terms of devils' feelings. For example, he couldn't understand the mental pain he put Yuuki through by forcing him to transform. Therefore, as he is described by CCC leader Kirio Kikuhara as a "quiet man" with "a deep understanding of devils,' he is severely reprimanded by Takashi Sawazaki for the key knowledge that he lacks.
Ishimaru is highly intelligent and calculating, as he can make false statements and false work history without being noticed. He is very poker-faced and level-headed, which makes it hard to know what he is thinking. When he was in the CCC, he managed to keep his identity hidden from F Squad, and although he had only joined the CCC in order to gain intel, he was loyal to the organization and appeared to be trustworthy. On the opposite spectrum, upon becoming the leader of F Squad, he was skeptical of his fellow members' investigative capabilities, given their inability to expose his real identity and his objectives until much later.
Following his desertion from the CCC and F Squad's disbandment, Ishimaru's true personality began to surface. Positive changes occurred as he began to understand devils more than before. He also began liking F Squad's atmosphere and it's members, despite initially seeing them as too imbecile. Even though they worked as comrades for a short while, it is clear that Ishimaru desires to reunite with them. Ishimaru has since become more considerate of others, and more expressive in general. He whole-heartedly thanked Tsukasa for saving Yuuki's life, referring him as "one of my men", and he also was the only one who comforted Tsukasa during her breakdown after temporarily breaking up with Yuuki. Ishimaru is good at reading between the lines, which is why he knows how to handle precarious situations and why he can predict if something's going to happen.
Ishimaru describes himself as a person who needs an excuse for doing things, such as checking up on one of his old co-workers Yousuke Asami. Although claiming that something had happened which made him think about Asami, Ishimaru actually just wanted to make sure Asami and his comrades were doing well.
Contrary to his appearance, Ishimaru is a highly capable fighter. He has good movements and his reactions are almost always on point. He is fast and agile and can quickly attack his opponents through proficient kicks and punches. He can overpower devils who are in a mild transformative state, and he can nearly keep in line with Yuuki in his fully transformed state.
Ishimaru is exceptionally good at lying, as he was able to fool both the CCC and F Squad during his mission for the MPD. His overly docile attitude highly contributes to this ability, giving him the appearance of one who doesn't care, rather than one who is keeping secrets.
- He has a bad habit of reading comics and light novels all night, so he always has bags under his eyes from lack of sleep - a trademark first suspected of being devil eye bags.
- According to Ishimaru himself, his local accent comes out slightly when he goes home, however, the majority of his coworkers have never had the chance to hear it.
- His original codename while working for the CCC is read as Jū-san (13), which is similar to how his other codename is pronounced/romanized, Jeison. It is possible that the name "Jason" was derived from this.