Sumi's days of poor mental health are certainly coming to a middle! Shiho goes to counseling! And someone's been having a weird time of things since April.
I think my favorite so far is managing to twist her into feeling inferior at her actual superior skill set because she can't conceive of having any positive traits that aren't borrowed from Kasumi.
(Pretty sure that in the original timeline Sumi died on or near her birthday, having chosen the least inconvenient method for others to clean up she could find.)
She hasn't yet done the work to reframe 'I killed her' into 'she thought I was worth dying for.' She can't comprehend that it needs doing, at the moment.