yeah you pretty much have to buy it from the landlord around the second time you pay rent this update
i have found out how... by wasting my life away you need to play to day 80 i think and do the church story line but it doesnt matter when, then at day 80 or higher make sure that your bot has 1.0 mood and just overall make sure she likes you n stuff. i find that giving her headpats and talking to her is enough. at some point when you go outside with jun the landlord will be there and im not spoiling this part... then another time it happens jun will actually be seen by the landlord and blah blah blah... at some point after that if you go outside by yourself the landlord should ask for 100k for the bathroom. you wont get the bathroom as soon as this happens youll have to wait a few days untill the rennovation crew come and theyll knock on your door and kick you out so they can rennovate. when you come home your house should have a shower on the right hand side of your room and boom there you go feel free to ask me any questions. but just make sure that jun likes you alot to trigger this...... your welcome