Risou no Tsuma no Takurami wa
considering there was so much from the original book to condence to fit manga form it is suprisingly faithful... the begining took a huge chunk and reworked it to get the important details in and had to cut my favorite scene (the original meeting of Emaline & Alex). It also left out the bits with Alex's friend John but he gets his own story next. I truly recommend finding the original version by Elizabeth Boyle... but be warned... it covers 13 books lol. John's story is begun with foreshadowing the history of his (& his eventual lady) with a giant debacle at the opera Emaline skips out on. That is not shown in the manga here (where it should have been)
Boukyaku no Kanata no Rakuen
I have also read the novel's of the other 3 men ^^
Akunaki Jounetsu