^^ While Ui does love her oneechan Iroha a lot, I don't think it's necessary incestual love like is with the Amane sisters. As for Touka yeah she really loves Iroha, I mean in the past she even calls Iroha onee-sama while Nemu only uses nee-san. Also Touka, Nemu, and Ui are shown to have a very close relationship in the past.