User blog comment:B214/Question and Answers/@comment-173.25.192.134-20131206030019/@comment-9339850-20131206030836

Its hard to classify them as "their novel" but Asia's is vol 6, Akeno has some of 4 and 7, Koneko's are parts of 5 and 11, Ravel's is 14, Rias has her moments in 1, 2, 10, 11, 12. Though im sure someone else could be more specific than me, but thats how i see it. Xenovia, Irina and Rossweisse have yet to had a moment where their character develops to genuinely fall in love with Issei, thats how i consider the volumes as "theirs"