|Voice Actor (jp)||Fumiko Uchimura|
Haruki Sagae (寒河江 春紀 Sagae Haruki) is one of the main characters of the manga and anime series Akuma no Riddle. She is a former student of the 10th year's Black Class at Myōjō Academy, who was in a competition with the other students who were trying to kill Haru Ichinose, with a reward of anything the successful assassin might wish for. She joined the Black Class because she needed money to support her siblings and her mother, who was hospitalized. The reward she requested for was for her family to be fed for the rest of their lives, even if she had died.
At the end of the story, Haruki got a job as a construction worker. In the manga it was also revealed that Haruki and Isuke Inukai are dating in the end, while in the anime's ending she was seen with some equivalency exam instructions. Judging by this scene in Episode 12, she may plan to send herself and her siblings to school.
Haruki has long red hair tied up in a ponytail with barrettes on her bangs and golden-brown eyes.
She wears a beige jacket over her school uniform, which is a white shirt, a red plaid bow, and a skirt, along with white socks and brown shoes. She usually wears bracelets, a purple hair tie on her right wrist and she wore long studded fingerless gloves before she attempted to kill Haru Ichinose.
Haruki is a tomboyish yet fashionable girl who is always shown eating snacks, especially Pocky (disguised as "Rocky" in the anime). She is also the typical lazy student who sleeps during class. She is always looking for thrills, but is very sensitive about her family's safety.
In addition, she is seen to have a strong will to fight when she wants to achieve a certain goal as seen when she lost to Tokaku Azuma but never gave up, even going as far as trying to kill Tokaku, Haru Ichinose and herself, in order to succeed.
Not much is known about Haruki's past except the fact that she came from a poor and large family with a sick mother and without a father figure in the household that she worked as an assassin to help provide for them.
Haruki was the third assassin to attempt an attack on Haru Ichinose who used Tokaku Azuma's name in a memo to call Haru into the gymnasium, where she personally handed Haru the advance notice with her name and attendance number on it. She then started to strangle Haru from behind using her garrote wire. However, Tokaku showed up, cutting the garrote wire from afar with one of her throwing blades, then knocking Haru out of the way. The two assassins then began to fight, Haruki with an iron knuckle glove and Tokaku with throwing blades. The two seemed to be even until Tokaku got serious and overpowered her. The lighting during this scene corresponds with their power struggle, at first one color then turning red when Tokaku has the advantage. Haruki refused to give up, even though she had lost. She then confidently said, "I win" as she cut a wire of a trap she had set, intending to take out the three of them using the lighting fixtures at the top of the gymnasium. However, they all survived, but Haruki was incapacitated with a broken arm. She became the third student to be expelled from the Black Class.
After the Black Class officially disbanded, Haru and Tokaku are seen receiving their diplomas and Haru even taking the diplomas of the 11 other former students of their class; Haru pledged to go on a journey to give each (ex-) assassin their earned diploma. During that scene it's shown (in the manga) that Haruki, who's now working as a construction worker, received a call from from her lover. Some of her o-workers ask if that's her boyfriend.
The next panels switching over to a beach scenery where Eisuke Inukai can be seen together with Isuke (Eisuke's daughter), who said that Haruki should hurry up to come back home or she would get angry. Eisuke then jokingly remarked that he's wondering how caring his adopted daughter can be towards her lover to which Isuke simply replies with saying she loves Haruki and can't help it.
Skills and Abilities
Haruki uses a garrote wire to carry out assassinations. It is used to strangle her victims and it is very effective despite the low chance of actually catching a person from behind with it, which is very useful in stealth jobs.
However, her physical assassination skills make up for that because they are exceptional. She wears a type glove that has an iron spiky surface at the top, which is very deadly if a person receives a hit. Her fighting skills are on a high level as seen when she was engaged in hand-to-hand combat against Tokaku Azuma, who was using throwing knives. To break up their even fight, Tokaku got serious and dominated Haruki by the culmination of their fight.
- The name Haruki means "spring" (春) (haru) and "narrative" (紀) (ki).
- Haruki's surname Sagae means "cold" (寒) (sa), "river" (河) (ga) and "bay, inlet" (江) (e).
- Haruki and Nio Hashiri both wear bows with their uniforms.
- Haruki has 9 younger siblings with one of her siblings' names is Fuyuka.
- Haruki wanted to buy a table of a smiling family after she got her first pay check from an assassination job.
- When Haruki got her first pay check, she bought a bottle of pink nail polish and she says that it doesn't suit her at all but she actually likes it. Even before her assassination attempt on Haru Ichinose, she painted her nails with a bottle of it.
- Haruki was the first assassin to personally give Haru the warning letter with her name and attendance number on it.
- Haruki is 166cm tall.
- Haruki's birthday is on 12th October.
- When Haruki was expelled from the Black Class, there were verbena flowers on her desk, which symbolize Family love. 
- Haruki's favorite snack is Pocky.
- Haruki's ending theme song is どうってことない Sympathy (Doutte Koto Nai Sympathy).T he song is performed by Fumiko Uchimura as Haruki Sagae.