Aika does have a manga, but I have never been able to find much about it or see scans online. If I am not mistaken, it is one of these manga that had a poor reception and was ended prematurely.
Really damn it, don't know why so many people including me post and repost Aika screenshots, but not a single person has ever posted Aika Manga scans.
Too bad it's all ryona on Aika and not on the delmos.I found it doujinsji agent aika :
[Mudai Document (Kari (Marron)] Agent Alone ~Kodoku na Agent~ (Agent Aika) [Korean] [Liberty Library] - E-Hentai Galleries