The Chiester Sisters Imperial Guard Corps, also known as the Pendragon Memorial Troops, Chiester Sisters (チエスター姉妹 Chiesutā Shimai?), or erroneously translated as the Siesta Sisters, are a collection of bunnygirl furniture in Umineko no Naku Koro ni. Their main weapon is a bow of light that shoots a tracking beam that can kill a target instantly. Dlanor A. Knox investigates the corps and discovers that their real world counterparts are Kinzo Ushiromiya's Winchester rifles. The defective rifle is represented by Chiester 556. In Twilight of the Golden Witch, it is revealed that the Chiester Sisters' original vessels were actually Maria's ceramic bunnies, one of which Rosa destroyed.
- The name "Chiester" is a corruption of the word "Winchester".
- The erroneous translation of "Siesta Sisters" by Witch Hunt caused the Chiester Sisters to be known as the Siesta Sisters to the English speaking audience. "Siesta Sisters" was thought to be the correct translation until Chiester 410's appearance in Ōgon Musōkyoku confirmed the spelling as "Chiester." This translation error was fixed for the Steam release of Umineko no Naku Koro ni.
- In Dawn of the Golden Witch, several unseen members of the Chiester Sisters are mentioned, each of which represent different guns, keeping with the notion that the depicted Chiester Sisters are incarnations of Kinzo's Winchester rifles. Chiester 127 is described as being able to pulverize a human target at 2 kilometers, a reference to the 5-inch deck gun which has a 127mm shell and a range well over 2 kilometers. Chiester 20 is described as having a fire rate of 6,000 rounds per minute, likely referring to the M61 Vulcan Gatling Gun which fires a 20mm round and has a fire rate of 6,000 rounds per minute.
- The banners the Chiester Sisters have on their left arms resemble the flag for Iceland (), however, their firing codes are written in Greek.
- The magical text that appears in the sound novels when the Chiester Sisters attack is transliterated from Japanese into Greek. When translated into English, the text reads:
Guidance System Version 07:
"Firing Guidance System Startup
Welcome to the Firing Guidance System.
Commence Data Accumulation...
Don't shake it. If we screw up now, it won't hit.
Formulating Firing Curve...
Formulating Firing Curve.
Forming as a Bezier curve.
This is filler, so please don't read it, okay? It's random.
All this English that I don't really understand sure is cool. Pretty awesome.
Firing Preparations Complete
Firing Preparations Complete.
If we shoot now, it'll hit.
...Assuming that the measurements are correct. Are we really good to go? It's totally automatic.
A number that will almost certainly hit."