The Citric Arc (2014)

Despite growing up in the same household and being only one year apart in age, Sienna and Azure often find themselves at odds. To Sienna, Azure's carefree nature seems selfish, while Azure views Sienna's pragmatism as snobbery. Because of this, both girls accumulate feelings of distrust and bitterness, which may make a true reconciliation impossible, unless unforeseen circumstances intervene.