It has two gardens, both with a gate: one contains a shed, a swing and a bench, where Rion and Lilia played together as children. The other garden contains a garage with a car, what looks to have been a pool, and a backdoor.
The ground floor includes: a dining room with a small kitchen, two bathrooms, a living room, a small bar with a jukebox, a counter with alcohol and billiards, and a great hall with the main door to the outside and stairs to the upper floor.
The upper floor includes: Albert Steiner's main office, a library, another bathroom, a great balcony, Rion's room with several toys, the Steiner's bedroom and a closet.
There are three secret passages in the mansion: one connects Rion's room with the downstairs living room via a ladder that can be opened with a painting, the second in the library that connects to a secret room with a computer where Albert Steiner recorded his message to Rion, and the last under the billiards which reveals a secret staircase that goes underground to a room with several computers and a desk with Dr. Pascalle's personal diary. It's unknown if it's his office, since Dr. Pascalle didn't actually live in the house.
The Steiner mansion is where Albert, his wife Elsa and their son Rion, lived. Dr. Pascalle and his daughter Lilia seemed to have been frequent and welcomed guests. The two doctors were colleagues and close friends, and Rion and Lilia became best friends that played together. The two men possibly started Dorothy's creation here and there is a book in the library detailing her development. When they discovered the A.I. they programmed had started the Family Program, they developed a virus program able to destroy her and an activation program for that virus. They implanted the first inside Lilia's mind and the latter in Rion's. As a result, the boy suffered a high fever for some amount of time. It's unknown if Lilia also suffered the same illness but she started to show telepathic abilities with Rion.
When suspicious men in black coats and a strange little boy were seen lurking around the house, Dr. Pascalle moved with his daughter to another place, believing along with Dr. Steiner that it was safer to separate the two children who had the power to destroy Dorothy. Some time afterwards, the men revealed to be actually Rabbits, attacked the manor. Despite his efforts to hide himself, Rion was found and kidnapped, and his parents were killed by the mysterious boy, the Galerian Rainheart, who tried in vain to get Lilia's location.
The murders were kept secret from the public as the newspaper in Michelangelo Memorial Hospital reports them as disappeared and the bodies of the victims weren't found. However, Dr. Pascalle's corpse was found by Rion after lifting a car up from the water of the pool that held his corpse.
Although Rion was able to successfully escape the hospital, he was not alone. Unfortunately, he is chased by a Galerian named Birdman who was also accompanied by a group of Rabbits. After having fought them, Rion discovers the Steiners' deaths, Dorothy, and his mission to find Lilia. First avoiding Birdman's attacks, Rion finally gets Lilia's old doll, and the girl is able to use her telepathy to tell him her location at the Babylon Hotel. Refusing to inform Birdman about this newly found information, Rion fights and kills him. After watching the Galerian die, he then leaves his house to return back to the city.
- Aside from Birdman, Rabbits are the only enemies fought, making this stage the location with the smallest variety of foes. By contrast, it has more files and information about the backstory than anywhere else.
- Despite the house being supposedly abandoned for a long time, electricity is still available. This is most likely benign but it's also possible that Dorothy was supplying electricity to the Steiner mansion to better deceive Rion about his parents' disappearance. Or quite simply it had it's own power source.
- Rion's house bares resemblance to the Spencer Mansion from the Resident Evil series both in appearance and role. Both houses are owned by a person with great wealth and are built in the middle of a forest away from the city (and in Resident Evil's case, Raccoon City). Also, both mansions have underground rooms built into them and had unethical experiments taken place there. Albert Steiner painfully wrote the activation program into Rion's mind when he was a child while Umbrella Corporation created the Tyrant in a laboratory under the Spencer Mansion and experimented on Lisa Trevor, an innocent teenager. Coincidentally, the Spencer Mansion gets destroyed in the ending of Resident Evil while in the Galerians: Rion OVA, the Steiner manor gets destroyed during the fight between Rion and Birdman. However, Dr. Steiner and Dr. Pascalle felt guilt and remorse for their actions, things the Umbrella scientists never felt.