上平 零

Birth year: 2034

Main character of episode 1
A 10-year-old boy born in a secret village. Rei has always been interested in the fascinating "outside world", however, following Subaru's order, a victory against Mikage in a one-on-one battle is required for every child who wants to explore life outside of the village.
As a result, he spends his whole childhood practicing in hope of getting stronger. But the peaceful life is broken, when Rei discovered an abandoned building in the village's dumpsite...

Main character of episode 2
The year is 2053. Rei, along with Aruru, formed the "Lost History Excavation" team (abbr. URH), where they would collect information in past events, by request. And one day, they meet Misora, with the request of finding her daughter and husband, who have left home 4 years ago.
Note: URH stands for Ushinawareta Rekishi Hakkutsu (失われた歴史発掘) - which is roughly translated into "Lost History Excavation"