This is my first review go easy on me aha..

Ilegenes: Giyoku no Koukyoukyoku is a continuation of Ilegenes: Kokuyou no Kiseki but 2 years later. The beginning isn't as attention grabbing like the prequel but the characters did get a nice hairstyle upgrade, heheh. Two girls were added to the story and in my own opinion they were average characters, but they did add some spice to the storyline.
(also the author decided to add the girls because a lot of people thought it was an all boys school)

I was interested to see more character development between Fon and Jacques (for example like how in banana fish and no.6 the main protagonists developed) but to be honest there ins't a whole lot, and if you are wondering, yes there was still a nice ending for the two in the end.

Going back to Ilegenes: Kokuyou no Kiseki, the ending in that was good overall. It gave a pretty good conclusion so I personally feel that you don't have to read this sequel because it doesn't add much to the main story and you can do without it. This feels more like an anime ova if it was animated. Of course it's still worth reading if you want more of this series but I feel as if it's not a 'need' to read. I am a little disappointed to give this story a 7/10 given that I gave Ilegenes: Kokuyou no Kiseki a 9/10 but you might still enjoy this, enjoy reading!