Ao Oni is a survival horror game where a group of people wander into the haunted mansion of the Ao Oni (Blue Demon). As of version 6.23, you play as Hiroshi and his group of friends including Mika (The Girl), Takeshi (The Coward), and Takuro (The Leader).
The story begins with Hiroshi and his friends exploring the haunted mansion. After hearing a plate shatter in the kitchen Hiroshi heads off to investigate. He heads back to his friends only to find them scattered and the door locked. He sees a mysterious shadow walk past the door and is unable to open it. Hiroshi heads upstairs and finds Takeshi in the closet, scared out of his mind. Hiroshi wanders into the library, grabs the key and is chased by the AO ONI. Wacky Chase Scene. HIroshi finds a random handkerchief and takes it with him.
Hiroshi runs into Mika in an upstairs room and the girl refuses to move from that room. He later meets Takuro on the first floor and Takuro agrees to search the first floor while Hiroshi goes everywhere else. Hiroshi eventually finds his way into the basement but hears a rather feminine scream and rushes back to the room where Mika is. He then finds the Ao Oni EATING Mika's face before hunting after Hiroshi. Wacky Chase Scene. With Mika dead, he goes back to the basement and explores.
Upon finding a key on top of a shelf, Hiroshi finds Mika in the basement. She then transforms into the Ao Oni. Wacky Chase Scene. Hiroshi then meets Takeshi in the annex, blaming himself for suggesting they all come into the mansion, and then he runs out. Hiroshi later finds Takeshi in a room, with a noose and him hanging over it. Takeshi has hung himself. Coming back later, Takeshi's body has fallen off the noose and he turns into the Ao Oni. Wacky Chase Scene.
Hiroshi uses the basement key and heads to the Annex Basement. He finds Takuro, who has a broken ankle and is forced to hide in a closet for the remainder of the game. Hiroshi finds the rope ladder to escape the mansion and returns for Takuro. Takuro joins the party. The Ao Oni is waiting for both of them at the rope ladder and they run away. Takuro however trips and killed by the Ao Oni. Hiroshi has to explore for a new exit and finds a room with a big cage, FULL OF AO ONIS! Hiroshi grabs the crap he needs and proceeds to run the hell out.
Hiroshi heads into the old building and finds a Blockman Oni. Wacky Chase Scene. Hiroshi eventually finds Takuro who is NOT dead and they form a party once more. After some more exploring Takuro turns into an Ao Oni. Wacky Chase Scene. Hiroshi finds the passage out through the old building and runs home. Hiroshi states that he never sees his friends or the monsters from that night ever again.
The game mostly plays as a survival horror game where you try to escape the mansion. You collect and combine items as they interact with the environment. All the while you must outrun the Ao Oni, who appears scripted but from where is more randomly oriented. Any touch with the Ao Oni will lead to instant death.
There are many different Ao Onis aside from the main Ao Oni.
Originial Ao Oni - He is seen as a terrifying big-headed monster. He is not as fast as Hiroshi but is incredibly strong. He does not seem capable of opening jail cells, seen from when Hiroshi hides out in a jail cell as the Ao Oni begrudgingly stares him down. He feeds off of humans evident form when he ate Mika's face. Everyone that dies in the mansion seems to turn into an Ao Oni. While Takuro and Mika were killed directly by said Oni, Takeshi may have either killed himself or looked as if he killed himself.
There are also many Onis found in the Oni room, trapped in a big jail cell.
Hulk Oni- A buff and well built oni. Slower than most onis.
Blockman Oni- A square oni that is faster than the normal Ao Oni and charges in large strides.You run into one at the study found in the old building.
Hunchback Oni- He's like an Ao Oni but his back is hunched over, hence the name. He is the one seen locking the door when Hiroshi heads in.
Blob Oni- The blob oni is this mass of squishy-ness covered in eyeballs.
Encephalo Oni- This Oni is pretty much just a big head with the lower half of tentacles. Many fanarts feature this one as a jellyfish-like creature.
Flying Oni- An Ao Oni with spikes all over its head and only moves by floating.
Toothed Oni- An Oni that looks like a regular Ao Oni except with bag ass fangs.
Takuro Oni- It looks like an Ao Oni with Takuro hair. The Oni that Takuro turns into after he is killed by the Ao Oni. This Oni is seen as more intelligent as it actually impersonates Takuro and joins your party before turning on you. It's shown to be able to alter forms at will.
Takeshi Oni- The Oni that has Takeshi's hair style. It's unknown as to whether he really killed himself or if he was killed by the Ao Oni. He turns into the Ao Oni which may have more to do with the mansion, or alterations to the body.
Mika Oni- The first Ao Oni to facade as one of your friends. She has the hairstyle of Mika naturally. She is first found in the basement pretending to be Mika but not to the point of speech. She silently transforms and hunts down Hiroshi.