Her outfit comes from her single "Portrait", released late 2014.
I had a more challenging time choosing which anime chibi to accompany her, since I normally just pick roles that were more recent. Except, Aki hasn't had much anime roles besides Sidonia no Kishi in 2015 (that I am aware of). Thus I resorted to choosing the ones that I personally liked, haha. I believe it worked out in the end.
Most definitely one of my favourite seiyuu, I do hope she gets many more notable roles soon~