Kikuka is 100% crushing on Ririku. This whole thing is the trope of "character A is crushing on Character B while on outing that could be seen as a date, while B is too dense to see A as anything other than a friend and sees outing as just two friends hanging out". No girl or guy in Kikuka's shoes would act the way she did without having a romantic interest in the other character. TLDR, Kikuka gay as fuck.