Yo Uei (上井 陽 Uei Yō) is a pre-petrification human and former policeman. Originally a member of the Tsukasa Empire, he faked his death after Chrome's escape to avoid the blame, then eventually joins the Kingdom of Science after the stone wars are over.
As penance, he worked with Yuzuriha to rebuild the statues that were destroyed by Tsukasa. Yo also worked in the farming division under Taiju. However, he is constantly butting heads with Magma due to each other's naivety in their respective worlds.