This Demon Door can be found just inside the front gate of Brightwall and to the right. For this Demon Door you just need to bring your own child to it and perform a happy expression (sometimes you don't have to and it automatically says he/she is beautiful). This requires you to have either adopted or conceived a child. Beyond the door there is a house full of Jolly Skeletons. Upstairs is where the chest is located, it contains 3 summon creature potions and 25 guild seals.