SAO makes sense for this one, since it starts in two months, but the other times she was at the studio? HF premieres in half a year so recording now is too soon imo.
Maybe they previous times it was for Historia.
(translation from the greek that @yuki.n answered me on fb)
Her Grandpa had died during WW2 in this island of Phillipines https://en.wikipedia.org/wiki/Luzon
There was a related documentary on NHK and her mother told her " i want you to watch that one". While leaving for the war, the grandpa left behind a letter saying that he wants to be a better husband and father. The letter survived till today and Yuki hold it in her hands.