With her dislike of Yuzu and Mei's relationship, Matsuri uses the secret photo she took at the shopping mall to blackmail Mei into fooling around with text-pal on Christmas. Meanwhile, Yuzu knows nothing of this and struggles to bake a cake for her first Christmas together with Mei. While her excitement builds, Mei comes home and breaks the news that she won't be able to join their Christmas Party due to student council work...
That was day we started 
acting like sisters.
Von dem Tag an waren
wir wie Schwestern.
Ese fue el día que comenzamos
a actuar como hermanas.
Ese fue el día que comenzamos
a actuar como hermanas.
C’est à partir de ce jour
qu’on est devenues comme des sœurs.
Da allora
o dia em que começamos
a agir como irmãs...
И с тех пор мы стали будто сёстрами.