One half of the series' main couple. She was friendless until she met Yuu in middle school, and as a result becomes jealous whenever Yuu gets close with others. Other times, she's a very friendly and cheerful person who likes imagining about other yuri couples and approving of any that she does see.
Shipper on Deck: Ships her friends together. After witnessing Kotone and Shizuka kissing, she begins to imagine Yuzu and Kaede having a similar relationship. After finding out Rina is always staring at Mitsuki she starts shipping them too. Nothing can convince her otherwise.
Terrible Artist: She tries to draw "Harry-chan" in Yuu's notebook to keep her from falling asleep in Chapter 4/ Episode 2b. The results are unanimously declared creepy and awful.
Yuri Fan: Haruka isn't just in a yuri relationship, she also gets excited about others being in one.
What Is This Thing You Call Love?: Haruka doesn't really understand the difference in loving someone as a friend and loving someone as a couple. She didn't even realize she and Yuu were considered a couple till Mitsuki told her what couples do.
The other half of the main couple, and the youngest in the Sonoda family. She acts childish sometimes, but otherwise gets along with the others well. Yuu enjoys physical education a lot —she's not good at any other subject, though.
Book Dumb: Absolutely has no aptitude in studying whatsoever.
Clingy Jealous Girl: While not as much as Haruka, she does get jealous whenever the latter also doesn't pay enough attention to her, such as in episode 5. She even goes so far as to headbutt Haruka before the latter can kiss her sister Mitsuki during a rehearsal between Snow White and the Prince.
The Ditz: While she has some street smarts, generally she is lacking in the the intellectual department. For example, in episode 8A, she didn't have second thoughts on whether same-sex marriage is even allowed in Japan when she heard about going to a wedding. Haruka always meant going to someone else's wedding.
Tsundere: More towards kissing Haruka than toward Haruka herself. This can be counted as foreshadowing that Yuu is more aware of what their relationship is than Haruka is.
One half of the secondary couple, in a relationship with her cousin Kotone. Shizuku is introverted and largely kept to herself until high school, when Kotone inspired her to try new things. She's not very good at expressing herself, as her expressions are either overblown, or send mixed messages.
Unknown Rival: Kotone's little sister considers her a rival for Kotone's affection because whenever Shizuku came over to their house Kotone would stop teasing her and start teasing Shizuku. Shizuku herself feels she should be the one whose upset since she was the one being teased.
The other half of the secondary couple. Kotone comes from a wealthy family, but lives with Shizuku's family for convinence. She is energetic and playful, and enjoys teasing the other girls occasionally. Upon entering high school, she resolved to make the most of her time there.
Arranged Marriage: The reason she is living with Shizuku is because her parents want her to marry.
Cool Big Sis: Her younger sister hates Shizuku because of the attention Kotone gives her. Kotone herself seems to hold her older sister in high regard.
Stepford Smiler: Episode 7A reveals that Kotone is not as happy carefree as she seems.
The Tease: While she is completely devoted to Shizuku she isn't above flirting with and teasing other's, such as Yuu and Haruka.
One half of the third pair of girls, though not as a romantic relationship. The class representative and childhood friend of Yuzu, she greatly enjoys toying with others, whether it be through teasing or pranks. She's also quite perceptive, and able to pick up hints of romantic feelings from others.
Kaede acts cool and collected and teases everyone a lot, but she gets really attached to the people she's around, and can't handle sad stuff because it affects her too much. This is evident during the third year graduation party, when she hides her face behind Yuzu in order to hide her crying from everyone else.
She is also the first of their friends to figure out that Yuu and Haruka are dating and that Mitsuki has a crush on Haruka. She also seems a bit upset that they are keeping it a secret though she can understand why.
Yuri Fan: She later becomes aware of Haruka and Yuu's relationship, and approves of it, though she only lets Mitsuki know as much. She also suspects Kotone and Shizuku may be in a relationship as well.
The other half of the girl pair, Kaede's childhood friend, and the Only Sane Man of the group. She tends to be the recipient of jokes or outbursts from others.
A-Cup Angst: Ironic, since she is fourth in size and has a least a B.
Allergic to Love: Becomes super embarrassed when anything about love and relationships is mentioned.
In a series with characters who are in romantic relationships or are aware of others' romantic relationships, she's the only one in the main group who fits neither, and even gets embarrassed when the subject of love comes up.
This is sent up in episode 10's extra segment where she's the only one to point out that all Rina does is smile.
Yuu's older sister and the student council president at the start of the series. She's the more studious, serious one of the Sonada sisters, but is also spacey at times. She's suspicious of Haruka and Yuu's closeness, and fantasizes about Haruka a lot.
Accidental Misnaming: When she first meets Yuzu, she can only remember the name was a citrus fruit, which leads her to try "Mikan" and then "Lemon". Mitsuki continues to call Yuzu "Mikan" despite being told otherwise.
Clingy Jealous Girl: Haruka has this perception of her this way in episode 5, although Mitsuki thought giving Yuu her drink was just her being sisterly since they like the same flavor. Haruka's perception would later prove to be accurate when Mitsuki takes measures so that Haruka and Yuu don't get too intimate.
Covert Pervert: For all her denials, she sure fantasizes about Haruka a lot.
I Want My Beloved to Be Happy: After realizing that Haruka doesn't really understand love and that even as she was confessing all Haruka was thinking about was Yuu, Mitsuki decides to give up and support Haruka and Yuu.
Shipping Torpedo: At first she refuses to admit Yuu and Haruka are even in a relationship or that she is in love with Haruka, but after catching them making out she out right forbids the two from being with one another. She gets better about it though.
Sibling Yin-Yang: Mitsuki acts more mature and is not good at sports, compared to Yuu.
Stalker with a Crush: She gets Yuzu and Kaede to report to her what Yuu and Haruka's relationship is. Episode 5 reveals that she often goes to Haruka's class to secretly look at her.
Suspiciously Specific Denial: When Kaede tries to talk to Mitsuki about Yuu and Haruka's relationship, Mitsuki says there is no way its true, that Haruka isn't that kind of girl, and the Haruka is just being overly nice. Later Keade becomes suspicious when she realizes that Mitsuki only mentioned Haruka.
Even the Girls Want Her: In-universe. Following the graduation ceremony, several girls tearfully plead for the second button of her uniform, which is a romantic gesture in Japan. They are also much more crushed that she is graduating then they were for Mitsuki.
Nice Girl: She's kind and helpful, and doesn't have any personality quirks.
Unrequited Love: Seems to have a crush on Mitsuki, who has an unrequited love herself for Haruka.
Satellite Character: In the anime most of her time on-screen is with Mitsuki, and her role is largely as the vice-president who has a crush on Mitsuki. In the manga, however, her role is expanded as she strikes up a close friendship with Yuu, much to Haruka's jealousy.
Schoolgirl Lesbian: She has a crush on Mitsuki but its not until they have graduated that she even begins to have a chance.
Motif: A moustache, which stems from her interest in them, like the decoration on her pen and the gifts she gave Mitsuki and Rina.
Older than They Look: Because she is so short and because of the way she talks, the girls, sans Kaede, mistake her for a first year...than a middle schooler. They are quite shocked to find out she is a second year and so a year older than they are.
Ooh, Me Accent's Slipping: She talks in several different ways all of which are done on purpose but occasionally slips back into a normal accent.
Romantic Two-Girl Friendship: In the manga she develops a bit of this for Haruka. She wants Haruka to act as her Cool Big Sis, despite being a year older than her, so that she has the courage to do her job as Student Council President.
Skinship Grope: Vigorously massages Haruka's chest after noticing how big and soft they are, later does the same to Mitsuki.