Try this:
1. Go here:
C:\Users\your_user_name\AppData\Roaming\RenPy
or press your explorer path and write %appdata% and you'll see RenPy folder, then look for the ImoTsuyo one.
2. You should see the ImoTsuyo folder with saves and persistent file, make a backup (just in case, not strictly necessary) and delete the whole folder (just ImoTsuyo one, not RenPy, or you'll delete your other Ren'Py games saves).
3. Go to where you unzipped ImoTsuyo v19.1 and (make backup), delete the folder "saves". Or unzip the downloaded file once again in other folder.
4. Try starting the game again, steps 2 and 3 would delete your persistent data and saves, but if you're new player that's not a problem, if you played it before, copy the saves and delete the original.
5. The game should properly start now.
6. If not, try disabling internet and open the game, see if that works.
7. If not, tell me again and I'll check again, but my game has no problems on my tests.