|“||Knowledge and rules of thumb are not everything, but they do help in making quick decisions.||”|
Anime | Manga thumb
Replica resembles a rabbit head, and is black in color. It has two white slits for eyes and a thin purple line of light across its body resembling a mouth. It also has two appendices on the top of its body which resemble rabbit ears, and two other, foot-like appendices on the underside of its body, which seem to serve as a landing support, but were never seen in use, as Replica is always floating or flying.
Being Yūma's guardian, Replica always provides advice for him, telling him what's right and wrong. However, he does not interfere in Yuma's direct decisions as it believes Yūma's choices are his own. It also assists him in battles, like when preparing certain seals for Yūma and making Yūma's attack more complicated.
Replica is Yūma's guardian, so it is very protective of him. It also frequently gives Yūma advice and helps him in battles.
Like Yūma, Replica trusts Osamu. It serves as a link between the two of them, and like it does with Yūma, it frequently gives Osamu advice and sometimes helps him in battles.
- (To Osamu) "Nice to meet you, Osamu. My name is Replica, I am Yūma's guardian." 
- (To Yūma, on multiple occasions) "I cannot make that decision. Only you can."
- (About Kōda Unit) "They seem pretty stupid, so it's possible they're being manipulated." 
- Replica's voice actor, Hideyuki Tanaka, also voices Yūgo Kuga and the Narrator.
- This trait wasn't kept in the Primo TV dub, where Replica is voiced by Marco Soriano and the narrator by Michael Dobson.
- The model for its creation was Ashihara's rice cooker.
- Viza referred to Replica as a Tropoi autonomous Trion Warrior. It is unknown what Viza meant, but "Tropoi" (Τρόποι, Trópoi) means "decorum" in Greek. According to Border Briefing File, it may or may not be a Neighbor country.