Rewrite is nothing NOTHING like grisaia in any way...and the main character in some route behaves like a complete moron and clueless about everything around him(with kotori's route specially!)
Sharin is very similar to grisaia in many ways, the mc specially they share a lot of things although i think kenichi is better than Yuuji
It has comedy, a very good drama, school life, some action and some really amazing plot twist that you wont see them coming at all add the perfect MC with the perfect antagonist (Masaomi) and yes you have almost the perfect vn