The 3DS thumbstick add-on is known as the Circle Pad Pro in the West, Capcom has revealed.
The name was mentioned by Resident Evil: Revelations assistant producer Tsukasa Takenaka at a recent Capcom preview event attended by Eurogamer. It also appears in the upcoming game's options menu screen, seen by Eurogamer.
In the horror action game, if you have the Circle Pad Pro, you're able to adjust the settings to select the "Type D" controller layout. This, Takenaka said, lends the game a third-person shooter feel. There is also an option to calibrate the Circle Pad Pro.
Speaking to Eurogamer following his presentation, Takenaka said using the Circle Pad Pro is "the right way to play the game".
"It was for us kind of a no brainer," he said. "As soon as we found out Nintendo had this peripheral, we thought this is something we can use to provide another bit of customisation for the game. We instantly decided to support it.
"When we decided that we thought, we have to do it fully, we have to create a whole other control scheme based just around this peripheral. We went ahead and did that, and we felt it was the right decision and it paid off because it feels like the right way to play the game."
Nintendo shocked its fans when it revealed the 3DS circle pad attachment. The move was seen by many as a radical attempt to make the handheld better suited to Monster Hunter - one of the best-selling games in Japan.
For Capcom, however, it was about providing a control scheme that made Revelations feel more "natural".
"For certain people, playing the game with the Circle Pad Pro, they may find it's easier to control the characters, and therefore it does make the game a little easier.
"But in terms of priorities, the thing most important was providing players with a control scheme that felt most natural for them. Basically, something that made it natural and easy to control the character. The controls fade away and you become part of the experience. We felt a lot of people might resonate with this control scheme and that's why we decided to put it in."
The Circle Pad Pro name was spotted last week after Nintendo filed a trademark for it. We know Revelations will be the first game to use it, suggesting it will launch on or before 27th January.