Well yeah, but the copyright infringement is a really, really thin line.

For instance... Group of people travelling somewhere to fight something that's bringing destruction to the world - Gensoumaden Saiyuki.

How many times has that been done before? Hell, that was my first NaNo project (farm boy, farm hand, younger sister and undead priestess going to fight person killing off the world), and I hadn't even read Saiyuki then. It's even the basic premise of Steven Erikson's books, although he's got rather more characters and they get really confusing after a time.

It is a very thin line, but it's also one you get past by not actually using any place names, character names of dialogue. There's little people can do about 'inspired by', that's how TV movies get to completely butcher up their version of newsworthy events. ;) They only ever get into trouble for it if they write something that concretely states their inspiration.

I mean, the amount of manga I've seen that is just like every other manga out there. After all, Kare First Love's been published, with characters that look near exactly like Kare Kano's and no doubt a plot near exactly the same - downside with highschool romance dramas, really: they're pretty generic.

Even one of the most original manga I own - Ray, a story about a girl with X-ray eyes - is unoriginal in its premise: the girl was created so people who needed skin grafts or had accidents or problems that required something like a new heart, lung or leg could simply take the body parts from the children in the unit. This has also been done in Michael Marshall Smith's novel 'Spares', a short story also of his, and the movie The Island (which was actually rather derivative of Spares, even down to escaping clones, yet I combed the credits and Marshall Smith wasn't credited at all - and since the character that escaped in his short story - the precurser to his novel, in fact - never actually MET the person he was a clone of, they had no need to credit it, even if it was nearly exactly the same story in places).

So like I said, it depends mostly on people using names, places and dialogue. Skirt enough around it, and no matter how blatantly it might be referenced, nothing can be done...

Shame though, since Marshall Smith's book and short story are great, and he could use more readers...