Chapter 023 is twenty-third chapter of Volume 4.
Nanami sees Tomoe leave, carrying Ryuo's eye. He chases him then gets picked up by Mizuki on his snake to catch up. Nanami planned to explain the situation to Tomoe but Mizuki claimed that it won't work and the only way to get it was to steal it. They stop at a house and Nanami sees Tomoe hugging a sick girl whom he'd gotten the eye for. Tomoe asks the girl to live with him forever. Mizuki smiles, knowing that Nanami was feeling the jealousy he felt over Tomoe. Tomoe decides he must go and tells the girl she must drink the medicine while he was gone. Mizuki tells Nanami to get the eye now that Tomoe had left. Suddenly, the girl cries out in pain, the eye in her hand. Nanami gets it then tries to feed it to the girl, surprising Mizuki. He asks what she was doing and Nanami explains that she couldn't let someone die in front of her without doing anything. Nanami fed the eye and Mizuki takes her back to the current time. As a compromise, Nanami plans to pay Tomoe's debt not from something of the past, but from something from the present. She wakes up, her body sore from time-traveling. Nanami asks if she can meet Isohime, her words possibly the key to saving Tomoe. They go to her cave, scaring away her human customers. Nanami tells her to take the Dragon King's eye from her body. Isohime agrees but wishes for 30 years of Nanami's life. Mizuki says that she shouldn't trust someone like that but Nanami explains that 30 years wont kill her, but Tomoe only had a day left to live. Mizuki leaves, unable to understand Nanami. Isohime takes out the eye, making Nanami faint. Isohime cackles, planning to take both the eye and Nanami's life. Mizuki reappears telling Nanami she should've listened. He kisses her to become her familiar, feeling the hesitation in his heart disappear, then proceeds to protect her from Isohime.