Yotsuha Miyamizu

Yotsuha Miyamizu (宮水 四葉) is a side character in Kimi no Na wa.. She is Mitsuha's younger sister, an elementary-school student, and a member of the Miyamizu family, where she participates in rituals for her family's shrine to create kuchikamizake as a shrine maiden. She and her sister live together with their grandmother, Hitoha, in a rural town called Itomori.

Appearance
Yotsuha is a young girl with light brown eyes and black hair which she wears in pigtails with two different hairbands. She is usually seen wearing a blue T-shirt with an orange hoodie on top, white shorts, pink-colored knee-length stockings and brown shoes.

As a teenager, Yotsuha's hair grows out longer, but she still wears it in pigtails with two blue hairbands. She is seen attending high school with a standard uniform.

Personality
Yotsuha is very level-headed, smart and independent for her age with sharp instincts, always waking her sister up in the morning and helping with chores around the house. However, she claims to see the world like an elementary-schooler and still acts like a cheerful and energetic young girl her age. Yotsuha also states that she is aware of her lack of understanding but is constantly trying to improve her knowledge.

She is more devoted to the Miyamizu family and its traditions compared to her older sister, though she is carefree and quite oblivious with the things surrounding the family and traditions, such as comments and criticism from other people, which Mitsuha describes as "pre-pubescent lack of concern". However, like her sister, she does appear to be tired of the traditions, like making braided cords at times. She also knows that Mitsuha isn't on good terms with their father but is confident that they can easily make up; being unaware of how relationships between people can be complicated.

Mitsuha mentions that Yotsuha comes up with many, and at times, weird ideas. Yotsuha also thinks that her sister is somewhat crazy but loves her despite the situation.

Background
Yotsuha is the second child born to Toshiki and Futaba Miyamizu. Being a Miyamizu, Yotsuha was taught about the Miyamizu shrine and traditions from an early age, and both her parents were both active in the Miyamizu traditions as well. Yotsuha had a happy childhood with her parents and older sister, but that changed when her mother died from a disease when Yotsuha was about three years old, leaving her with few memories of her mother. Following her death, her father was devastated because he couldn't do anything to save his wife. He then rejected the Miyamizu shrine and its traditions to pursue a career in politics, confessing that he only loved his wife Futaba and not the Miyamizu shrine. Refusing to live with their father, Yotsuha and Mitsuha began living with their grandmother, Hitoha, instead.

Original timeline
By the time of 2013, Yotsuha is nine years old and a fourth-grade elementary-school student at Itomori Elementary School.

Yotsuha is first seen waking her older sister, Mitsuha, up for breakfast, though she overlooks as Mitsuha (actually Taki Tachibana in her body) feels up her breasts. Mitsuha eventually returns to her own body and she joins Yotsuha and their grandmother for breakfast, though they remark how Mitsuha is acting "normal" since Yotsuha claims she was acting really odd before.

Several days later, Yotsuha and Mitsuha perform a public Miyamizu tradition where they make kuchikamizake, an ancient traditional way of creating sake involving chewing rice to intake yeast for fermentation which makes the sakes become "half" of the sisters. After the ritual, Mitsuha exclaims that she hates her life and she wishes to live as a handsome Tokyo boy in her next life, much to her Yotsuha's dismay; remarking how her sister is an idiot.

Everytime Yotsuha overlooks "Mitsuha" feeling herself up when she wakes her up for breakfast, she expresses her discontent at her "liking her boobs".

One day, Taki wakes up in Mitsuha's body and accompanies Yotsuha and Hitoha to leave the ritual alcohol kuchikamizake, made by Mitsuha and Yotsuha and thus becoming "half of their souls", as an offering at the Miyamizu shrine on a mountaintop outside the town. Yotsuha is enthusiastic during the trip, though she expresses some concern when "Mitsuha" is confused about some Itomori expressions and the comet.

On October 4th, Yotsuha attends the autumn festival, where the peak of the Comet Tiamat's brightness would be visible. However, the comet unexpectedly crashes onto Earth and destroys the town. In the process, it kills Yotsuha and most of the other Itomori residents.

Alternate timeline
After Taki drinks Mitsuha's kuchikamizake, he is able to go back to 2013 before the incident in order to prevent it. When Taki wakes up in Mitsuha for the last time, his crying fit makes Yotsuha leave, muttering that she has gone mad and had "lost it".

Taki (while he is in Mitsuha's body) desperately pleads for the residents of Itomori to not attend the festival and evacuate, but he is coldly rejected by Yotsuha and Mitsuha's father and scares off smaller children. Yotsuha thinks that Mitsuha has been acting even stranger than before, to which she inadvertently reveals to Taki that Mitsuha had skipped school one day to go to Tokyo and search for him.

Later that day Mitsuha (returned to her original body) convinces her father to evacuate the residents to prevent the disaster, to where Yotsuha is last seen with her grandmother and father in his Mayoral office. Subsequently, it is revealed that every resident survived the comet thanks to Mitsuha's actions. Yotsuha decides to continue her life along with most of Itomori's residents by moving to Tokyo.

Main Story (2016)
Taki is seen finding Yotsuha's name in the records of fatalities. Though Yotsuha isn't seen in the 2016 timeline, she should be about twelve years old when the time is altered and she survives the incident.

Epilogue (2021)
Following the destruction of Itomori, Yotsuha has moved to Tokyo, presumably with her family members. By the time of 2021, she is 17 years old and seen attending high school in the city.

Trivia

 * Her name "Yotsuha" (四葉) means "four leaves". The same applies to her grandmother Hitoha, which means "one leaf"; her mother Futaba, "two leaves"; and her sister Mitsuha, "three leaves".
 * Yotsuha speaks in a dialect like most Itomori residents, having the suffix -ya in her sentences.
 * In contrast to her sister, Yotsuha is a morning person and always wakes up at six during weekdays.
 * It is unknown with whom she lives at the end of the film, as Mitsuha is seen living alone in her own apartment. Presumably, Yotsuha lives with her father and/or grandmother.