There is no official personality, but according to my headcanons: silly, overly energetic. Btw she's a robot. Se loves fried chicken the most.
Speaking style
Speaks in gentle, lilting cadence with sing-song upticks; uses short, wholesome phrases and a comforting rhythm
Lore hook
In 2017, production was started on creating Adachi Rei. After successfully building a life-sized Hatsune Miku robot, missile39 went on to create their own original character robot. On February 15, a CAMPFIRE crowdfunding campaign was launched to help fund the construction of the robot. The goal was set for 3 million yen and surpassed that goal, hitting a total of ¥3,596,499 from 184 backers.
The rewards for backing were set to be sent out in December 2021. To go with the robot, a singing voicebank was to be created for UTAU. Rei's voice would be modified from various digitally synthesized samples to create a voicebank capable of singing in Japanese. The samples were created through an additive synthesis process in Audacity, and modified to create a more genuine, anime character-like, robotic voice. The parts for her robot were digitally modelled and 3D printed. Her UTAU voicebank was finally completed and released on October 12, 2019.