From what I understand, the incense did not alter her mind. Remember, her necklace was given to her by the monk's second, female disciple? That was likely an older version of herself. So, since she chose to remain in the capital, that older version of herself disappeared, and with it the necklace it could've given, as well as the memories of it.Lmao. What a terrible Buddhist monk. Kills a butterfly like it's nothing (thought Buddhists were against killing any creature), he wants to marry a preteen, and to top it all off, then he messes with the timeline by drugging her using mind-altering incense to make her lose her memories.