It's mentioned in the last chapter that Ilegenes is based on a novel, in which Fon is the antagonist. Does anyone know the title of the novel, and maybe even where I could read it in English?

Thanks!

After seeing reading the final chapter of this part of the story (Manga Updates has a link to the sequel on the series' page), I did some searching for any translations of the novel as well...

I haven't been able to find any groups translating it, but I did find a summary of the first volume (+the first chapter of volume 2). The summaries are very wonderfully detailed, but the person who did them stopped updating their live journal April 2012, it seems, (I hope nothing bad happened).

Also, based off the omake and what I read from the summaries, the light novel came out first, but the manga is based on events that happened to Fon /Fon's past preceding the light novel. The sequel manga series will continue to fill the gap between the manga and light novel. Due to the nature of the light novel, taking place after events in the manga (that have been scanslated so far...I can't read Japanese or Chinese, so I do not know how far the sequel is or plans to go), the very first chapter has a lot of big spoilers for the rest of the series. (But, I read anyway.)

Starting from chapter 1, the summaries can be found here: http://issyapir.livejournal.com/4156.html

Dear kind soul, thank you so much for the detailed reply! In that case, I'll probably hold off reading the summaries for now. 😉