Birthday: August 1 Hanyuu is the mysterious "transfer student" in Matsuribayashi-hen. She has a pair of dark colored horns on her head, one of which is chipped slightly (however, no one seems to notice or mention them, with the exception of Takano, who calls her a "monster"). In fact, she has appeared to Rika all her life, but only in Matsuribayashi-hen and Miotsukushi-hen did she gain the power to interact with others, posing as a distant relative of Rika's and given the name "Hanyuu Furude." Like many of the characters, she can be frightening when angered, and with her spirit-like nature, her appearance can change with her mood until she takes a physical form. She is very meek and often makes the noise "Au au, au au…" when she is nervous or uncomfortable, or sometimes while trying to make a point. She also tends to end her sentences with nano desu (ã�ªã�®ã�§ã�™?, lit. "it is so"). She dislikes alcohol and kimchi, which Rika imbibes in large amounts as punishment when she finds Hanyuu annoying (as both Hanyuu's and Rika's senses are linked together). She mentions that she is a "being above humans" after being sacrificed to atone for the sin of humans, while both Rika and Takano describe her as a kind of deity. Rika refers to her as "Oyashiro" when talking with others (evident from Shion's chat with Rika in Meakashi-hen) but does not personally think of her as Oyashiro; instead, she sees her as a close friend. In Higurashi no Naku Koro ni Rei, Hanyuu tells Rika that she was sacrificed to atone for the sins of the people of the village, and Hanyuu asked ÅŒka Furude (Hanyuu's own daughter and Rika's ancestor) to kill her and then make the village a better place. She is the one responsible for the eternally repeating June 1983, which she created in order to save Rika from being murdered.
Setsuna Kashiwagi, suffering from a Heart desease and his own useless Life only causing trouble to his beloved Sister, made a contract with Kanna and Rena to sell his Heart after a year, but for that he needs to be protected while his Heart is changing.
Kanna is Rena's older Sister and a potential Successor for the Head of the Oni-clan, if she can gain Setsuna's Heart. Later on it is revealed she has romantic feelings for Setsuna.
Middleman is a demon who dresses up as a gentleman: complete with a suit, top-hat and monocle. He seeks out people who no longer see a value in their own life and offers them a deal, their life a year from that day for a large sum of money. To seal the deal he has the person drink a potion called the "Banrikou", which this potion also marinates the organ in question to be devoured by the one who paid for it after the year. This potion gives off an aroma which lures other demons. He also appears to be a bit of a flank, as Kanna commented that he always forgets to inform the customers what they are getting into.
Hakuu is a mysterious pink-haired female who dabbles in underground biological experiments, surgery and investigation of monsters known as C.L.I.S. (Creatures Left In Secret). She is apparently much older than she looks. People call her a witch.
Darkrai is a black, shadow-like creature. It has a small head with a white fog-like ghostly substance billowing from its head covering one of its bright blue eyes, and also has a red spiky growth around its neck. It has skinny arms and long black tatters hanging from its shoulders, similar to the tail of Raichu. It also has black, claw-like hands. It has the slight appearance of an hourglass figure and appears to be wearing an old, ripped cloak. It normally doesn't have any sort of legs, but it is able to extend stilt-like appendages in their place. In self-defense, Darkrai also appears capable of retracting its head and white "plume" into the pit atop its torso fringed by the aforementioned red growth. Source: Bulbapedia