Seems like Chapter 3 confirms that she isn't a succubus. The nurse is the succubus. But it's not like our MC doesn't have the skills to fumble herself into looking like one. At this rate she will definitely have her own yuri harem, considering she just made the cyclops girl come. The nurse accepts the MC as a succubus, and I hope the MC harem will include the nurse in the future. It would be awesome if our human MC could make a succubus fall for her.