Sounds like an excellent storyline. However, I found a couple of grammatical errors that you might want to correct.

"A thousand years later, there was a powerful king, King Chronos, heard of a legend of the fantastic summons and their powers that he set out to find the book."

-the sentence structure doesn't make sense. Might want to rethink that one.

"Once open the summons and their necklaces burst from the book and fled from the castle."

-might want to put a comma between open and the. I had to stare at that sentence for a while before it made sense to me.

There were a couple of other ones similar to that, and near the end of the second paragraph you called him Kind Chronos instead of King Chronos. The only other thing that really stood out to me, though, was this:

"The young prince keep the mystical book in case of the king's family actually broke through the seal and reeked havoc on their world in revenge of the king's death."

-a grammatical disaster. First off, it should be kept, not keep. Secondly, you either skipped over the word "any" for between case and of, or you need to delete the of. And, thirdly, it's wreaked, not reeked. Reeked is the past tense of the slang of something smelling really gross. Wreaked is the word you were meaning to use.

Shows promise, but there're some punctuation errors at the end of the first paragraph (And memories that should not have been forgotten. were lost.) and second paragraph (Soon he had a baby girl and lived happily ever after. but for how long.?) Had they been anywhere else I might have missed them.