The first three-quarters of Kirai are pretty standard shoujo stuff, if perhaps a better-than-average version of it. And then things take an unexpected turn that make this a decidedly more original and mature, if somewhat harder to process, manga. Strict girl meets playboy who mistrusts women, but has no problem sleeping with them. They end up step-siblings, so she sets out to correct his bad behavior. They slowly fall for each other. If you've read much shoujo or josei before, you've surely seen a variant of that plot line. Kirai is a particularly good example of it, although for the first30 chapters or so not an especially original one.

And then, over the course of the last ten chapters or so, the manga takes an interesting and completely unexpected turn. I don't want to get into spoilers, but an unexpected event occurs, followed by a small time-skip forward, and suddenly this fun if unoriginal manga becomes something altogether more interesting, mature, and compelling... if also a bit harder to read at times.

A couple warnings: many of the notions of sex are very outdated, particularly regarding sexual assault and consent. (Seriously, having sex with a girl so drunk she is almost passing out is rape, not infidelity.) Also, the artwork looks very outdated; the manga ran from the late 1990s to the early 2000s, and I think the art would have been a bit old-school even then. It's not bad art (though the handsome guy often comes across as funny looking); just old-school.

Ultimately, this is a manga about learning to trust the people that you love, and it is willing to push on that concept pretty far. It may start out a stereotypical "bad boy meets virgin" shoujo, but it ends up as one of the more thoughtful, dramatic shoujo romances that I've read.