Is this sentence right?

If that is the meaning, then 'how' is wrong and should be deleted.

AnonymousThe person is trying to say now he realized she is a devil.

now? how? Are you confusing the two?

He has just (now) realized that she turned into a devil.
He has just realized how (in what way, by what means) she turned into such a devil.

how is needed if you are talking about the means by which she changed

The word "how" is sometimes informally used to mean "that".
See definition 15 .

YankeeThe word "how" is sometimes informally used to mean "that".
See definition 15 http://dictionary.reference.com/browse/HOW?r=66.

Yes, but ...


Ken has just realized HOW she turned into such a devil.
=
Ken has just realized that she tur

Hi Jim

Yes, I'd agree that this informal use of "how" seems relatively unlikely in this particular sentence, however I thought that the informal usage was worth mentioning because (1) I just couldn't rule it out completely, and (2) because I thought the OP might have been posting a sentence he or she had actually heard used with that meaning.

Yes, that makes sense.

CJ