|Age||early 30s (Himatsubushi-hen), late 30s (Matsuribayashi-hen)|
|Image Song||BUCHIKAMACE Tekkoudan|
Akasaka Mamoru is a character in the Higurashi no Naku Koro ni series. He is the main protagonist of Himatsubushi-hen. He is a young police investigator at the Metropolitan Police Department of Tokyo. He is the husband of Akasaka Yukie, and the father of Akasaka Miyuki. His wife stays in the hospital while she is pregnant with their child.
In Himatsubushi-hen, Akasaka appears somewhat naive and inexperienced, due to his young age. Later, he proves to be quite cunning when he plays mahjong with Ōishi and his friends, thus earning their respect. But in Matsuribayashi-hen, from his the martial art training, he becomes a very skilled and experienced officer. In the original Sound Novels, Rika states that the chances of Akasaka s survival and leaving the village are low, because he usually gets killed by the kidnappers during the investigation in most worlds.
Akasaka is sent to Hinamizawa to join Ōishi's department, which is investigating of the kidnapping of the cabinet minister's grandson. This kidnapping is suspected to have been perpetrated by the anti-dam movement, the "Onigafuchi Guardians".
Upon his arrival in Hinamizawa, he befriends Furude Rika, who speaks to him with her Adult Voice about the future deaths of herself and his wife. In an untold world, he regrets not being able to save his wife and Rika, and learns "Traditional Style Karate" to clear his mind from all the pain and hopes to relive the time before Himatsubushi-hen to save them.
Through a fate's miracle in Matsuribayashi-hen, he inherits the "Traditional Style Karate" and uses it to single-handedly defeat a Yamainu Squad and their leader, Okonogi. He decides to save Rika from her prophesied death, as both a friend and as payment for warning him of his wife's death before it could occur.
The manga and anime versions of Matsuribayashi-hen are different in that the manga greatly expands the story. In the anime, Akasaka discovers the curious connection between Koizumi and the Irie Clinic. In the manga, Rika is able to visit an Akasaka who has coped with the loss of his wife and unborn daughter by immersing himself in his job and karate. The Akasaka in this time regrets not heeding Rika's warnings in the past which led to the death of his wife and Rika. While not fully explained in the manga, this meeting allows a connection to the Akasaka in Rika's current time-line who wakes up as if having a nightmare at work. He remembers Rika and discovers Koizumi's payments to the Irie Clinic. Either way, Akasaka comes to help Rika. Much later in the manga, during the festival, Rika meets Akasaka and his wife and daughter. She refers to Akasaka as "father" which causes his wife to accuse him of having a "love child" in a bit of comic relief.
In TIPS of Tsumihoroboshi-hen (The Demon's Script), Akasaka returns to Hinamizawa with his colleague Sawada in 2005. There they discuss details concerning Great Hinamizawa Disaster and its connection to Takano Miyo's File No 34.
Akasaka also appears in Reunion, based on The Demon's Script. He meets Ōishi and Sawada to visit the remains of Hinamizawa years after the Great Hinamizawa Disaster and discuss how it was connected to Takano Miyo's File No 34. There they also meet with an adult Ryūgū Rena.
Akasaka is a tall, muscular young man with black hair and dark brown eyes, save in Matsuri where they are light brown. In Himatsubushi-hen, which takes place in 1978, he appears appropriately younger.
During his free days, Akasaka wears a cream-colored jacket over a dark purple T-shirt, grey jeans (blue in Matsuri) and grey shoes. In Himatsubushi-hen when in his police station, Akasaka wears a blue suit over a white collared-shirt and a green tie. When he goes undercover he wears a cream-colored shirt over a dark purple T-shirt, grey pants and grey shoes. He also carries a camera to look more like a tourist.
Akasaka comes to Hinamizawa to investigate the kidnapping of a cabinet minister's son in Himatsubushi-hen which takes place in 1978. He finds a very young Rika sleeping at the bus station. He will later see her watching her from at distance. Unbeknownst to him and to readers and viewers at this stage is Rika has lived this existence multiple times before. In this arc she speaks to him in her Adult Voice as she predicts who will die each year as well as warns him of the dangers to his wife and unborn child. Naturally, he neither understands nor believes her. For her part, Rika appears resigned to this, and she even seems cruelly playful as she can be in lives she deems futile from previous experience.
Depending on the arc and the relevant media depiction, Akasaka's wife dies but his unborn daughter is saved, or he is able to save them but still does not understand Rika's warnings and fails to help her in time. In Matsuribayashi-hen Akasaka follows his suspicions and returns to Hinamizawa to help Rika as a critical piece to break her fate. However, in one of the many failed worlds depicted in the third season's Nekodamashi-hen, he rapidly develops the Hinamizawa Syndrome and murders Rika before setting himself on fire.
In most arcs, his wife suffers a fatal fall in the hospital. In ones where physicians save his unborn daughter, he raises her as a single parent. The manga version of Matsuribayashi-hen expands their role comically in that both meet Akasaka and Rika during the Watanagashi Festival and Rika calls Akasaka "daddy." It is implied that Rika and Miyuki become friends.
The two meet in Himatsubushi-hen as part of the investigation of the kidnapping of the son of a cabinet minister. They meet decades after the Great Hinamizawa Disaster but they still have no understanding concerning what really happened.
While not made clear in the anime, Okonogi is the Yamainu he fights in Himatsubushi-hen. They appear to remember one another when they confront each other again in Matsuribayashi-hen.
- He is voiced by Daisuke Ono in the anime and by Takehito Koyasu in the drama CD. Both of them are known for voicing characters that are rivals/enemies with each other, most known example of this being Jotaro and Dio in the JoJo's Bizarre Adventure anime.
- His English voice actor in the dub of the 2006 anime is also Dio's English voice actor, while the voice actress of his daughter would later voice Jotaro's daughter, Jolyne, in JoJo video games.
- Daisuke Ono is also the voice actor of Ushiromiya Battler, the main character of the Umineko no Naku Koro ni series.
- Although not appearing in the live-action movie adaption of Onikakushi-hen, Ōishi tells Maebara Keiichi that he "lost a close friend in the investigation of the murders in Hinamizawa". Ōishi likely refers to Akasaka, though he could be referring to his surrogate father.
- A homonym of his given name, まもる (護・mamoru) is Japanese for 'protect'.
- According to the manga, Ryukishi07 implies that he wrote Akasaka as a self-insert.
- Matsuribayashi-hen (manga) Chapter 2. Ryukishi07: "In this volume, we have the long-awaited appearance of Akasaka. I didn't think that myself...I mean, that Akasaka would be such a popular character. Maybe he's Higurashi's ever-important, standard "good-looking guy" character."