User blog comment:DeathGodPrayer/Talk About What You Want!/@comment-162.202.198.72-20130913051624/@comment-24.4.76.157-20130915072135

There is a short story where something happens with kuroka that hasn't been translated called  Records of the Breast Dragon Emperor's Pleasure Trip where she might get closer to issei, look up her image gallery on this wiki to see what I mean. It might be a while but lets not give up hope because unlike any other possible harem candidate, she actually semi-lives at Issei's house :)