Formerly Abin Sur's Green Power Ring, this weapon came into the posession of Nanoha Takamichi of Earth 2814. Unlike other power rings, it is capable of acting independently, at one point (as of chapter five) acting autonomously of Nanoha's finger. When fellow Green Lantern Yuuno Scya, AKA, Ferret Lantern, called Ring-chan on this behavior, S/he replied "I have been given no orders to do anything," Chapter two noted that Nanoha's relationship with Ring chan was that she "Was known for teaching it how to sing and encouraging it to develop into its own independent entity (also a cause for lots of hearings). Even afterwards, centuries later, that particular Ring insisted on being referred to as 'Ring-chan', was the only Ring who also acted as an independent Corpsman as times, and tended to get angsty every 365th day, supposedly on the death of the Green Devil herself."
It is also capable of long distance communication without a green lantern's pemission, contacting several superheroes and magical girls to save Nanoha after she was defeated by Vita.
It should also be noted that Ring-chan has developed a rivalry with Raging Heart for Nanoha's attention, often referring to the device as " pink frilly phallic object".