Thanks for the info, at this point I'm trying to 100% like a pokemon game lol. besides endings I managed to get all besidesReach the 29th of June and the game will mention you're close to the end of the game. When you hit 3rd of July (7/3) the game will end with the girls and MC's son will go and celebrate. If you have the girls lust to level 5 you should recieve messages from them. Yui, Kaede, Rena and Aoi will celebrate at the same location whilst Taeko will celebrate some where else. To 'celebrate' with the corresponding girl you'll be given an series of option on who to answer, click on (girl)'s message and it'll trigger said ending. (I might need to re-check to be sure since I have a save file a day before the ending and it doesn't trigger for some reason).
Yui - 1F, I'm guessing thats a hallway scene like with Kaede? not sure how to trigger it though at this point.