Kouichi always thought of Mao as his little sister, but when he wakes up from a dream and she walks into his house, he doesn’t even recognize her. Probably because, after living in France for several years, Mao is definitely not anyone’s little sister anymore! To further complicate things, Koichi’s mom has invited Mao to stay at their house while she attends the same high school as Kouichi and their mutual friend Kazuki. But given that Kouichi’s been trying to build a relationship with Yuumi, the revelation that he’s now sharing accommodations with a non-related girl is definitely going to cause some emotional waves. Or maybe a tsunami by the time Kazuki’s sister Nana, her best friend Narumi and all the other kids at school get overly involved. Young love and teenage angst are the rule as histrionics and history classes collide in the spellbinding KIMIKISS ~ PURE ROUGE!
Kouichi wakes up from a dream only to have a cute, strange girl intrude into his home. It is only when his friend Kazuki arrives that he is able to remember that the girl is his childhood friend, Mao, who moved to France 2 years ago.
Ever since he returned from school Kazuki has been thinking Eriko. He asks for some info on her from Akira but is unable to get anything helpful.
It's a new school day and Nana and her friend Narumi are messing about with their frogs. When Kouichi arrives with Mao, Nana uses this as a chance to invite Mao to a welcoming party.
It's been a month since everyone went to the karaoke box together and Mao is annoyed at Kouichi, who hasn't made any progress with Yuumi. Meanwhile, Mao has been receiving a lot of love letters recently but she only considers them to be a nuisance.
Mao goes on a date with Eiji to a live jazz show. Kouichi is spending more time with Yuumi, using the movie club screenplay as an excuse. Kazuki has been agitated - even Mao has noticed, so she gives him some words of advice.
Kazuki decides to continue the "experiment" with Eriko. Before that, he goes to make amends with Asuka. Mao should be feeling the strain of the midterm prep, but she has no motivation. So Kouichi & Kazuki get everyone together for a study session.
Midterms are over so now they have time to think about the movie. Seeing as how Kouichi did a good job on the synopsis, what's left is to find an actress for the female lead. They discuss this at Narumi's family restaurant.
Mao has been acting weird ever since the kiss she shared with Eiji; Kazuki has been suspiciously cheerful as well. Mao can't seem to face Eiji so she does her best to avoid him in school. While Kouichi is stuck with Akira, Kazuki goes out with Eriko.
Everyone has met up to talk about the movie synopsis, which is missing something. Kouichi is still thinking about the chance encounter with Mao and Eiji. Akira suggests using the school's swim tournament to get a girl in a swimsuit for the movie.
Tired of the bad atmosphere, Kouichi heads out to the bookstore, where he runs into Eiji. Meanwhile Kazuki is having soccer practice with Asuka. The next day Mao goes out on a date with Eiji but Kouichi is stuck at home with a cold.
Everyone is at Mitsuki's mansion, to check out the location where parts of the movie will be filmed. There's an uncomfortable atmosphere around Kouichi and Mao, and they can't even talk to each other after what happened the previous night.
It's a new school day, and Kouichi is somewhat worried about Yuumi after what happened at the train station. On the other hand, Kazuki is in high spirits with things between him and Eriko going surprisingly well.
With summer vacation fast approaching, Kouichi somehow managed to finish the script for the movie. Kazuki has been really nice to Asuka lately and just when she starts to realize her feelings for him he tells her that he likes Eriko.
Summer break has arrived. Kouichi tries to make as many memories with Yuumi as he can while she is still around.
The filming isn't going as smoothly as planned, with Yuumi as the female lead. A replacement is needed, but the only person suitable is Mao. Later, Kouichi takes Yuumi to the beach and Mao goes to see Eiji perform in a live concert.
Mao still feels unsettled after seeing Kouichi kiss Yuumi. Kouichi and Yuumi go on a date to watch a movie in the cinema. Kazuki and Asuka practice together, but he's been getting distracted. Once she discovers the reason, she confronts Eriko.
Kazuki has been taking time off after being dumped by Eriko and Asuka is worried, seeing as how she caused it all. Kouichi and Yuumi have been spending the remainder of their summer together, yet he still feels lonely at home with Mao not around.
In the rain, Mao dumps Eiji. She returns home soaked and ends up with a fever. Kazuki suddenly gets a call from Asuka. They go back to her place to have a chat. Kouichi continues to worry about Mao.
The new school semester has begun but that is the least of Kouichi's worries, as he is still quite shaken up after Mao declared her love for him. All the classes are preparing for the upcoming school festival.
After running from the filming, Mao ends up meeting Eiji by coincidence and they talk. Kouichi is worried about Mao, and Yuumi is worried because she's sensed the feelings Mao and Kouichi have for each other.
Mao is already making preparations to move next Sunday. At school everyone is busy preparing for the School Festival and even Nana and Narumi are making steady progress.
At school Kazuki has noticed that Kouichi and Asuka have both been acting weird lately, so he tries to do what he can to help them. Kouichi is still brooding over Mao. The gang throws a farewell party for Yuumi.
Akira has completed all the movie club's preparations for the school festival, so all that's left is for Yuumi and Koichi to enjoy their last day together.
The Kibana School Festival is in full swing; however Kazuki is somewhat troubled because Eriko is nowhere to be found and he thinks it may have to do with Asuka.
Megumi Kuryu questions the frivolity of love: its meaning, why people need it, and more importantly, can a prefect such as herself experience it. Megumi’s thirst for enlightenment leads her into encounters with friends as she tries to find her answer.