Chapter 81 of Kamisama Hajimemashita manga.
Nanami realizes that there was a way to save the dying Tomoe; by going back to the past and making it so he never got the curse. She tells Mizuki to get the incense burner but he gave her a helpless look. Mikage puts her in a bubble and tells her that though going to the past was a good idea, she will be trapped in the bubble until she has calmed down. Mizuki wonders if he was going to lose his master all over again. Meanwhile, little will-o-the-wisps who live in Mikage Mountain support Nanami in saving Tomoe because he was kind and had brought them here. Nanami realizes that if Tomoe never came, the will-o-the-wisps would also never have come, as well as Mizuki. The bubble pops and she looks for Mizuki. Mizuki, alone in Yonomori's shrine, tells himself that even if he would return to his lonely self before Nanami came, he was willing to give the burner to Nanami if it was the only way to save Tomoe. Nanami looks for him in Mikage shrine and finds a twig of a plum blossom tree and she knows where he is. She goes to him, telling he was a fool and hugging him, promising not to change the past and abandon him, but decided to only go to the past to find out the cure for Tomoe's curse. With that, she finally goes. Meanwhile, Mikage knows that Nanami had gone, but for some reason, is glad she had.