Okay, I have played a few hours and have now arrived in the laboratory, the maps are getting bigger and bigger and the only thing to do is to collect keys to open any doors, on the way there are numerous enemies that just annoy you because the map is too big and with each new map section the mobs respawn. During my playtime I have seen many scenes of the girls, but not one with Ena. Maybe I'm doing something wrong, because she won't talk to me when we're at the inn. (I need to unlock the first H-scene with Ena to start a dialogue with her, according to the game's message).
Bummer!