Mizuki has white slightly parted hair. He has green snake-like eyes, white eyelashes and pale skin. He is seen typically wearing Japanese traditional clothes, just like his rival and fellow familiar, Tomoe.
Mizuki had led a very sheltered life until he met Nanami, something Tomoe scathingly points out on more than one occasion. Inexperience notwithstanding, Mizuki can be very clever and even manipulative. He still loves Nanami in his own way, and so is very jealous of her obvious affection for Tomoe.
He has tried several times in various ways to drive a wedge between them, without success. He is extremely naive and is shown to possess a child-like wonder and innocence in the ways of the human world and the things in it. As he continues to spend time with his new land god and her friends his world has expanded, but he remains by and large a rather goofy, lovable baby.
Nanami begins as Mizuki's love interest, but his affection for her seems to have solidified into more of an older sister/younger brother relationship. This is ironic, considering that he is several hundred years her senior. He frequently comes to her for protection and sympathy when Tomoe behaves in a cruel manner, and competes with Tomoe for Nanami's affection, not as a potential lover might, but rather as a little boy vying for his beloved older sister's attention.
He is very loyal to Nanami, even refusing to acknowledge Mikage as the land god of Mikage shrine in her place. He also begs her to be careful to avoid changing the past during her travels, as he doesn't want to miss meeting her in the future and return to his lonely life at the abandoned Yonomori shrine.
Tomoe and Mizuki began as enemies, and their relationship has only improved marginally from there. This is mainly due to Tomoe's understandable resentment (in light of past events) of Mizuki being allowed at the shrine at all, much less as a familiar, and secondly because of their mutual jealousy over Nanami's affections. While Tomoe is extremely upfront with his dislike of the white snake shikigami, Mizuki wages a much more subtle war against his fox senior, frequently attempting to manipulate Nanami and make Tomoe look bad.
While naive in the ways of the world, Mizuki frequently exhibits a definite shrewdness for relationships. At the god summit he helped Tomoe come to grips with his growing feelings for Nanami, because above all else, Mizuki wants his land god to be happy, even if it is at the expense of his own heart.
Yonomori Mitsuha is Mizuki's former land god, a water goddess of the Yonomori shrine. Her manifestation was a plum tree, and when she went into hiding, she left a beautiful one behind for Mizuki to remember her by. Mizuki later created his fantasy shrine with this tree as its cornerstone.
In chapter 82 we meet a very young and nearly powerless Yonomori, who has just been gifted a sacred shikigami egg. We are left with the understanding that this egg will one day hatch into the white snake Mizuki. Until Nanami, Yonomori was the only tochigama Mizuki ever served. He loved his kami very much and she returned his affection, encouraging him at the end of her life not to mourn her, but to find a companion and live out his days in happiness.
Mizuki becomes a temporary husband for Unari when Kurama tricks her and angers her. After accepting her for who she is and cares for her, she falls in love with him. However seeing that Nanami is the most important person for him, she allows him to leave.
Though she loves him deeply, it is questionable whether he returns her feelings. However, he still cares very much for her, not wanting her to feel the same loneliness he had, and promising to see her once every year to be with her.
- (To Tomoe) "You should be punished for trying to burn the shrine of a water god"
- (To Nanami, at the festival) "What is a candy apple? Is it sweet? Is it candy? Or an apple?"
- (To Tomoe, at the festival) "I can't stop shivering because I'm forced to hold hands with someone I hate."
- (To Nanami) "This plum tree is Yonomori-sama's favorite"
- (To Nanami, when she orders him to stop attacking Isohime) "Please say it again Nanami-chan! And bind me with the invisible chains!"
- (To Nanami, in his thoughts) "Do you still remember this plum tree? This is the place where my heart touched a human's for the very first time, even if its forbidden or whatever...I don't care anymore."
- (To Nanami, when Tomoe was ill from the curse) "If Tomoe-kun wasn't at Mikage shrine...I'd still be here at Yonomori Shrine...sitting and staring at the plum tree...I'm so lonely, Nanami-chan..."
- (To Yonomori-sama) "Yonomori-sama...Am I...going to lose my master again?"
- (Practicing the flute) "Wheeeeze."
- (To the onibi-warashi, when Mikage-sama has returned) "Nanami-chan is my only master. I don't care that Mikage-sama has returned. I won't let him dpo away with Nanami-chan"
- (To Tomoe) "I hate your guts. But I have the courtesy of not telling Nanami about what you did."
- (To Unari) "Unari's eyes are clear and blue, just like the Okinawan Ocean. I think it's pretty."
- (To Unari, about Nanami) "She is the most important person."
- (To Unari, when he's leaving) "Unari! I... will come here again. Once a year. Every year on this day. I will come see you."
- Mizuki is a skilled brewer of sacred sake, as his former land god was very fond of it.
- He possesses a sacred artifact called a time-turning incense burner which allows him to send himself and others back in time.
- Mizuki has a strong fondness towards ice cream and candy apples.
- Though he has exceptional skill making sake, it is revealed that he doesn't like other forms of alcohol such as whiskey.
- Mizuki was waiting for a god that would never come back, like Tomoe.
- Nanami is the second god Mizuki has served.
- Like Tomoe, Mizuki has romantic feelings for Nanami.
- "Mizuki" is a gender-neutral Japanese name.
- Mizuki fears Nanami disappearing and being lonely again, which is similar to Tomoe's fear.