The Erosion Meter is a term referring to the variables required to obtain the Rust Menu in .flow.
Explanation[]
The variables surrounding the Rust Menu revolve around viewing/interacting in disturbing events within .flow. This can range from being caught by a chaser to witnessing events that awaken Sabitsuki. The two main effects of increasing the meter can be seen on Little Sabitsuki in the Parade Ward, as well as in Sabitsuki's Room in waking life.
Little Sabitsuki[]
Healthy—This is Little Sabitsuki's default state, present at the beginning of the game. She sits upright in her bed, and has clean hair and a clean face. This occurs at 49 points and below.
Sick—Little Sabitsuki still sits upright in her bed, but her hair, face, and arms are matted with blood. This occurs between 50 points to 99 points.
Terminally Ill—Little Sabitsuki slouches in her bed, and her hair and face are still covered in blood. There is more blood on her arms, and her blanket has blood stains and is considerably more wrinkled. It is at this stage that Little Sabitsuki will grant Sabitsuki wth the Rust Menu. This occurs at 100 points and above.
Sabitsuki's Room[]
50 Points—A permanent blood stain appears on Sabitsuki's computer and keyboard. There is another small blood stain on the floor near the foot of Sabitsuki's bed.
100 Points—A large blood stain appears near the top-right corner of the rug, on the hardwood floor.
150 Points—A large blood stain appears to the left of the bookshelf, on the wall.
180 Points—There are two monitors hooked to the computer. At the foot of the left monitor, there is a small trickle of blood.
200 Points—There are three droplets of blood on the walls: one to the left of the door, one above the television, and one above the right monitor.
Changing the Meter[]
Increasing the Meter[]
Both the Blood, Pus, Rust Event and the Dying Girls Event increase the meter by fifty points upon first witnessing either event. Upon subsequent views, ten points will be added to the meter.
The Bar Kaibutsu Event will increase the meter by fifteen points no matter how many times the event has been viewed.
Depending on Sabitsuki's location, upon being caught by a Kaibutsu, the meter may or may not increase by a various amount of points. Being touched by a Red Demon will add three points to the meter, regardless of where Sabitsuki is located.
Decreasing the Meter[]
Interacting with the transparent Oreko in the Machine Room, located in the Starry Pier; as well as eating at the Sugar Hole; will decrease the meter.
Note that decreasing the meter heals Little Sabitsuki and removes a significant amount of the blood stains present in Sabitsuki's Room in waking life; however, the blood stain on the computer remains, no matter to what amount the Erosion Meter has been decreased.