I've just finished the game, and this is an absolute masterpiece. I've played a fair few harem games in my time, but this one is easily the best execution of the harem visual novel I've seen, and uses the medium to the fullest for fantastic comedy, engaging characters, and a genuinely engaging story.
The good ending was just lovely. I can't even validly say 'the only bad thing is that there wasn't more', because the game does everything it needs to and wraps it all up with a bow. As an undying fan of the harem genre, I can't express how great of an experience this was. It blew my expectations out of the water.
Superb work, and I'm looking forward to checking out Eternum.