Pixiv user tags: "Social inequality in breast size", "lap pillow for the curtain raiser" (re: first frame, previous page), "Bishoujo of oxidation", and "Social inequality in terms of oxidation"
Updated
Okay, some of you are probably thinking “Not the cliché sister setting again” or “Black tea and green tea aren't a sister relation at all”.The raw ingredient between these are the same.I wonder if this unfairness is caused by the oxidation as well...Strongly oxidized teaBoth of us are made from the same tea leaves.The scientific name for it is Camellia Sinensis. You better remember it.*squish**flap flap*Ye-Yes, that's right. The only difference between Onee-sama and me is the degree of oxidation. I-I can't breathe.
See wikipedia on tea classificationTea without oxidation