Say "I love you."

Say I Love You is a 2008 Shojo manga by Kanae Hazuki.

Quiet and unassuming, sixteen-year-old Mei Tachibana has spent her high school years without making friends or getting a boyfriend after an incident in her childhood causes her to believe that all people betray each other. When she encounters popular boy Yamato Kurosawa, he becomes interested in her and it is through their tentative friendship and blossoming relationship that Mei ultimately begins to branch out and befriend others.

This series contains the following tropes:

 * All Love Is Unrequited: Yamato's middle school crush on Arai, who only shows interest once he gets more good-looking, but by then, he isn't attracted to her anymore. Asami, Aiko, and Megumi have unrequited feelings for Yamato; Kai has unrequited feelings for Mei. Subverted with Nakanishi's crush on Asami, Masashi's crush on Aiko, and Chiharu's crush on Hayakawa. Their crushes were initially unrequited, but they were reciprocated in the end.
 * Beta Couple: Nakanishi and Asami.
 * Betty and Veronica: Mei and Aiko (later Megumi) for Yamato. Kai and Yamato for Mei.
 * Big Eater: Mei.
 * Birds of a Feather: Kai and Mei. They have both been bullied in the past, have difficulty with being looked at, being around a lot of people, or participating in group activities (e.g. karaoke), and thus they can understand each other fairly well and talk to each other easily.
 * Bitch in Sheep's Clothing: Megumi.
 * Brutal Honesty: Mei.
 * Childhood Friend Romance: Hayakawa and Chiharu.
 * Fake Out Make Out: Yamato does this to Mei to get rid of a regular at her bakery who has been stalking her, unwittingly taking her First Kiss.
 * First Love: Yamato's first crush, Arai.
 * First Name Basis/Last Name Basis: Upon meeting each other, Yamato quickly refers to Mei by her first name while Mei formally refers to Yamato by his last name. It is only a while after they start dating that she begins calling him by his first name.
 * Genki Girl: Asami and Chiharu. Megumi appears to be this.
 * Girlish Pigtails: Asami.
 * The Glomp: Asami.
 * Green Eyed Monster:
 * Mei's first signs of having feelings for Yamato are through her jealousy of his first crush Arai. After learning from Asami that Yamato seems to be able to kiss any girl (including Mei) instead of his crush, Mei feels insulted. Her jealousy only deepens when she learns that Yamato and Aiko had sex in middle school, but she gets over it.
 * Hayakawa envied Yamato because all the girls love him while he has to sleep around to get their interest.
 * Aiko was jealous of Mei because, in her perspective, Mei effortlessly hooked up with Yamato while Aiko pushed herself to lose weight and make herself look pretty in hopes that she would be noticed.
 * Yamato is jealous of Mei's friendliness with Kai and how natural it is for them to talk and understand each other. Kai's implied feelings for Mei, as well as Megumi's attempt to sabotage Mei's and Yamato's relationship by constantly telling Yamato how close Kai and Mei are, also doesn't help their situation.
 * Megumi cannot see why Yamato would choose such a "plain" girl like Mei for a girlfriend when he could have her and is determined to sabotage Mei's relationship with Yamato, as well as distance Mei from her friends Asami and Aiko, so she can get rid of Mei and have Yamato for herself.
 * Heel Face Turn: Aiko.
 * Heterosexual Life Partners: Mei and Asami. Yamato with Nakanishi and Kai.
 * I Just Want to Be Beautiful: Aiko and Megumi.
 * Jerkass: Hayakawa.
 * Kuudere: Mei.
 * Love Dodecahedron: Both Asami and Aiko had feelings for Yamato before ending up with their love interests Nakanishi and Masahi respectively; Megumi also has unrequited feelings for Yamato, who ends up dating Mei, who is the object of Yamato's best friend Kai's affections.
 * Malicious Slander: Asami suffers from this due to her breasts, causing people to think that she Really Gets Around or is involved with Compensated Dating. Yamato's younger sister Nagi ends up in this situation when classmates at school tease her about having a brother complex to the extent where she refuses to return to school.
 * New Transfer Student: Megumi transfers to the gang's high school in hopes of becoming closer to Yamato.
 * Oblivious to Love: Yamato towards Megumi, and Mei towards Kai.
 * Official Couple: Yamato and Mei, Nakanishi and Asami, Hayakawa and Chiharu, and Aiko and Masashi.
 * One Degree of Separation: Yamato has known Asami and Aiko since middle school. Hayakawa and Aiko are Friends With Benefits. Mei's co-worker Chiharu is the childhood friend of Hayakwa, who is also Yamato's friend. A regular customer at the bakery is Kai, who turns out to be Yamato's middle school friend who was bullied.
 * Opposites Attract: Yamato and Mei.
 * The Quiet One: Mei.
 * Really Gets Around: Aiko and Hayakawa. Naturally, both of them are Friends With Benefits until Hayakawa starts dating Chiharu.
 * Relationship Sabotage: Megumi tries to pull this on Mei and her relationship with Yamato by trying to get closer to Mei's friends and twisting Mei's moments with Kai to seem as though she's closer to Kai than Yamato. Eventually, Yamato, as well as Asami and Aiko, see through what Megumi is scheming.
 * The Rival: Aiko is this to Mei until she pulls a Heel Face Turn and decides to let Yamato and Mei be together. Megumi, a model who develops a crush on Yamato, later fills in as a rival to Mei. Kai becomes this to Yamato once the former begins developing feelings for Mei.
 * School Idol: Yamato and Hayakawa.
 * Shallow Love Interest:
 * Yamato's first love Arai, who rejected him in middle school because she wasn't his type. She only starts expressing interest in him once he becomes "taller and cooler."
 * Megumi, who is pretty much introduced as a self-absorbed model, obsessed with good looks, and is only after Yamato because he resembles a prince. Her whole motivation revolves around having Yamato as a boyfriend and her Establishing Character Moment is bluntly telling Yamato, who she only just met at a karaoke hangout, that she wants to date him for his looks.
 * Shojo Genre
 * Sickeningly Sweethearts: Nakanishi and Asami.
 * Single Girl Seeks Most Popular Guy:
 * Inverted. It is Yamato who first develops feelings for Mei, but she quickly reciprocates without initially realizing it.
 * Played straight with Megumi's crush on Yamato.
 * Slice of Life
 * Stalker With a Crush: A regular at Mei's bakery follows her in the first chapter. Mei ends up calling Yamato for help, which leads to a Fake Out Make Out. Chapter 2 has this Played for Laughs with Mei stalking Yamato and his interactions with Arai.
 * Three Amigos: Mei, Asami, and eventually Aiko form a trio.
 * Tsundere: Yamato and Aiko.
 * Wrong Guy First: Gender-flipped with Yamato and Arai. Yamato used to have a crush on Arai until she overheard her talking to her friends about how he wasn't her type. It is only once he's become "taller and cooler" that she shows interest, but by then, Yamato's already interested in Mei.