Strigliata by Kirijo Senpai
If the protagonist has not entered Tartarus once within the first 10 days, upon returning to the Iwatodai Dormitory that evening, Mitsuru will confront and scold him/her for slacking off and forcibly bring him/her to Tartarus just before the first Full Moon Operation. She will also stop the protagonist from leaving until S.E.E.S has started exploring Block 1 of the tower.