User blog comment:SpookyBoogie27/Light Novel Spoilers/@comment-24098614-20131223074221/@comment-67.176.158.104-20131223191311

I know he has become aware of Asia's feelings for him. At the end of volume 6 she kissed him. And in volume 7 Issei did say that he had come to notice Asia as a single girl. Even their classmates had notice how much closer they had become. So I guess base on that Asia has also been excepted into his harem.