Say "I Love You."

We are introduced to 16-year-old Mei Tachibana, who, after suffering a traumatic experience in making friends, decides to ditch making friends altogether during high school. She catches the attention of Yamato Kurosawa, the most popular boy among the girls in their high school, and wasted no time making friends with her, even giving her his number, despite the refusals, and even accidentally kicking him when she thought Yamato lifted her skirt a bit (it was just his pervy friend Kenji Nakanishi), earning the ire of Yamato's girl followers. She tried putting it at the back of her mind, until, one night, when a stalker followed her on the way home from her part-time job. Deciding to hide in a convenience store, she tried calling home, but no one answers. She calls Yamato, who rushes to the scene despite being at karaoke with friends at that time. Yamato wards the stalker away by pretending to be Mei's boyfriend...

Ever since that rescue by Yamato, Mei started having dreams about him being her protector. Later on she gets to befriend Asami Oikawa, who idolizes Yamato. It was from her that Mei heard rumors about Yamato kissing every cute girl in their school save for one girl named Arai, rumored to be his girlfriend. For this she refuses Yamato's invitation to karaoke. However, because Asami has big breasts, she is being bullied at school, and Mei even stands up for her, at the cost of her cheek. Asami accompanies her to the clinic, though Yamato has bandaged it up prior. Kenji, who is heading for the clinic after being hit by a soccer ball in the face, catches the two bully girls inside the school clinic picking on Asami and defends her, though a little misunderstanding about her breasts and his bleeding nose made her run away. With some encouragement from Mei, Kenji eventually confesses his feelings for her.

Yamato tags along as Mei intends to visit the parlor to have her hair cut, eventually becoming a date. On the way they meet Aiko Muto, along with her boyfriend Masashi Tachikawa, and eventually invites the two to a bowling alley. Aiko, who has a crush on Yamato after finding out her ex-boyfriend cheated on her, wonders what did he see in Mei, who looks not interested in him. When the two girls are alone Aiko bluffs Mei into leaving him alone, but it was in vain as Yamato followed Mei on the way out. Yamato momentarily loses Mei, but knew where to find her. Eventually he shows Mei his middle school, where he sheds light on his past, about not caring about anybody else as a middle schooler, even with his best friend who was being bullied. He says it's him who is having a hard time blending with others. For this Mei, who herself needs to trust others, tells him to trust others, else he will lose friends.

Mei has attracted the attention of one Kakeru Hayakawa, a guy known to have slept with many other girls, including Aiko. He then wastes no time in asking Yamato if he can hook him up with Mei for lunch with him. Yamato is unaware, though, that Kakeru has other designs for Mei, and, when Yamato was distracted by a phone call, he tried to convince her to be his girlfriend. But Mei sensed his motives and leaves him alone in an instant. Yamato learns of what happened, and when Kakeru starts badmouthing Mei, he punched him, saying she's his girlfriend. Kakeru tells Aiko about this the other day, but, despite being surprised about this development, she instead scolds him, that he will not be like Yamato. Mei appears to them, adding her impression of Kakeru. As he leaves in disgust, Mei, while recognizing Aiko's sacrifices, states that she is not giving Yamato up.

Yamato has invited Mei to his house; the pressure is almost overwhelming. Yamato’s little sister doesn’t pull punches when she sizes up Mei for the first time.

A new girl has transferred into Toumei, the rising idol Megu-tan and she has set her eyes on Yamato.