Quick note - under the Itch client, the game fails to launch (can't find executable). The exe is there, through further investigation (AppData/Roaming/itch/apps/Kare wa Kanojo) but the itch client itself can't launch it.
the game isn't meant to be run with the itch client yet for the simple reason that the exe is an installation program. I might make a version for itch client someday if it's highly requested. But for now, just get the setup exe and install it normally. ;)