Yumi was 10 when she first saw the work of a chi-blocker. When she was 13 she was able to observe a whole attack of chi-blockers. After that she decided to learn this technique herself since it seem to be the only possibilety to beat those who preform it. But it's easier said then done. Benders aren't allowed to train and know one really knows how it works. Maybe she has to stealth train or something like that...?
Hope you like it ^^
Yumi © TifaCroft
Chi Blocking © Avatar The Last Airbender/ Legend Of Korra