I literally told you, they can be gotten both on the same playtrough same as all scenes if you have at least "save" where you can load it, if you picked wrong choices, as for Emi scene it is a part of choice based event if you picked wrong, it will not happen. As for the "Oni" scene it may be "love path", it is a part of the "story" where you need to get "bug"once you there, you have to look for some, this scene trigger if you are going to her apartament to ask about them, simply if you have not seen it, you did something wrong.