In chapter 12 of A Silent Voice, collected in volume 2, Shoko has a fight with her sister Yuzuru, angry with her for getting Shoya in trouble when he helped her. Yuzuru's lines are spoken, but Shoko signs with no translation given. The chapter features four panels of Shoko signing across two pages; her words in the last are harsh enough that Yuzuru breaks down crying and runs away.
(I recognize that it may not be possible to recognize full sentences from a single manga panel each.)