I swept the harem by pretending to be weak

[An ancient time travel novel with a brain hole, no romance, the heroine is clear-headed, determined and has a goal] When Liu Zhirou found out that she, a good young person of the new era, suddenly became the emperor's concubine, she was very panicked, but she found out that she had a plug-in system, as long as she didn't let others know her strength, she could continue to extract skills from the system, and she was no longer panicked. Isn't it just being an invisible person? No problem! (Grades in the palace: Queen - Imperial Concubine - Concubine - Beauty - Talented - Baolin - Selected Concubine - Cainu) (This is a very strange novel?????)...