Zetta Scarlett Minamimoto is a genetic combination of Sho Minamimoto and Doctor Insano that resulted from an incident involving a cloning machine, three rubber bands, a roll of duct tape and a lock of Sho's hair.
She is also the half-sister of Fortune, but she isn't aware of this.
Not much is known about Zetta's past, not even to her parents. All that's known is that, due to the incident described above, she was created instead of the expected clone of Dr. Insano, and for that reason, he foisted her off on Sho and pretended she had never existed.
She recently joined the mistakes while pursuing a prospective Player who had recently vanished from the UG (this Player was later revealed to be the recently-resurrected Kurgan Junior).
Zetta and Sho have a fairly decent relationship (although he can be a bit embarrassing at times, and they have to pretend they're cousins in public), even if he is disappointed that, due to taking mostly after Insano, the only Reaper traits she acquired were a pair of small wings and the ability to see into the UG. Insano doesn't want her, only saw her once, and probably doesn't even remember her. She doesn't know about him.
She's only recently joined the team, and has very few concrete opinions of anyone. She seems to gravitate toward those who seem most knowledgable about what's going on.
Zetta is very nervous and awkward, has trouble approaching others, and seems to mentally "script" situations, plotting out what she thinks will happen and how she plans to respond. She tends to freeze up and panic when something unexpected throws her off. She's intelligent, and enjoys math and science (particularly chemistry). She's quite knowledgeable about explosives.