I remember reading "Yaoi would be nothing without a bit of Stockholm Syndrome" - and this sums up this manga pretty well.
An average bankteller that never did anything out of the ordinary gets kidnapped and raped while being a hostage.
Imagine yourself being hold a hostage and raped on a daily basis. Not a nice thought, huh? Our protagonist enjoyed it and fell in love with his kidnapper. This is just horrible.
The protagonist is made an average man who is engaged to the woman his parents want him to marry. Then suddenly he falls in love with his rapist. That's all there is
to it. It's just so unreal, it should be considered Fantasy genre.
So all in all: I do NOT recommend you to read this manga, it's a waste of time and your memory.