The futon bed back in my day was incredibly simple.  It was merely a mattress the could be folded and put away in daylight hours.  The one my parents had was a minimal brown foam padding that folded in thirds.  As a kid, we sat on them like large cushions, but that was about as sophisticated as we got.  It’s incredible to walk into a furniture store nowadays, when futon beds come in more forms than any Japanese grandmother would have imagined; bunk beds and loft beds.  In fact, she might be horrified.  But I guess that’s all part of the progress of Western society!  I must agree with her, though.  I like my simple mattress that triple folds into a silly lopsided chair cushion.