In the future of the beta timeline, Mayuri adopted a war orphan, Kagari. When their time machine was discovered and attacked, Kagari was sent back in time with Suzuha. During Suzuha’s mission, she lost Kagari. After Suzuha jumped forwards in time to continue her mission, she kept searching for Kagari. When Kagari was found, she was identified by the Metal Upa she has with her, a keepsake from Mayuri.

Correction

Um actually … Kagari didn’t have a Metal Upa, it was the Green Fairy Upa.

The Mayuri got the Metal Upa from capsule machine, but it was misplaced and ended up together with the time travel thesis in this timeline in 2010.

The Green Fairy Upa was bought from the store in the beta timeline after Kurisu’s death.