Talk:Steals and Wheels/@comment-14017325-20190207084654/@comment-4010415-20190208021244

Her eyes turning red is part of her Semblance, not a mood ring that tells us every time Yang is mad about something. We've seen from Weiss and Pyrrha that people can activate their Semblance by accident when feeling a high amount of negative emotion, so I really think that Yang's anger issues cause her to activate her Semblance by accident, hence her eyes turning red.

Ruby did mention to Maria in Volume 6 that there is a connection between emotions and Semblance.