At Final Battle in December 2018, Yu took part in a four way match for the ROH Women of Honor World Championship that was won by Kelly Klein, marking her first pay-per-view appearance.

[3][17] Yu made her first appearance with WWE in August 2018, competing in the Mae Young Classic tournament under the ring name Karen Q.

[2] From February to July 2019, she wrestled for WWE as Karen Q, primarily teaming with Xia Li on NXT house shows.

[18] In July 2019, Yu suffered a fractured lateral malleolus; she spent the next two years rehabilitating, undergoing two surgeries.

[19][21][22] In December 2020, Yu was reintroduced on NXT as "Mei Ying", the leader of the stable Tian Sha alongside Xia Li and Boa.

[20] In March 2022, Choo and Dakota Kai competed in the Dusty Rhodes Tag Team Classic, losing to Io Shirai and Kay Lee Ray in the finals.

[18] In February 2023, Choo suffered an unspecified injury; she was written off television to allow her to recuperate via an angle that saw her attacked in a parking lot.

[6] Her finishing moves have included a modified Boston crab (dubbed the Spring Roll), a fujiwara armbar,[6][10] and a rear naked choke.

[5] In 2020 and 2021, Yu portrayed the "enigmatic and destructive" character of Mei Ying, a 1,000-year-old woman who acted as a "Yoda" for the Tian Sha stable.