Dans cette série, vous êtes le héros et une une fille vient dans votre chambre. Durant les épisodes 1 à 4, vous découvrirez Yui Hanasaka, une lycéenne de 17 ans venue d'​Hokkaido qui est à Tokyo pour passer des examens. Les épisodes 5 à 8 sont centrés sur Natsuki Momohara, la petite soeur du héros qui est âgée de 14 ans. Lors des épisodes 9 à 12, notre héros retrouvera par hasard son amie d'enfance de 21 ans, Moka Aoshima.

Yui with you who bame a tutor and a student from a neighbor. In a space of just two people, the distance between the hearts gradually get closer. One day, the two go to a public bath and make a small but important "promise".

Yui serves home cooking as a daily thank you to you. While having a good time, Yui was terribly depressed due to the poor results of the mock exam. One a snowy night, a small and gentle time comes to the two of them who are about to take the exam.

Yui takes the exam with the amulet you gave her. And the seasons go around, and the tree-lined road where cherry blossoms dance. Yui reveals a special secret to you walking next door. It will surely be an important moment that you will never forget. And the two are--

My sister Natsuki comes to you who is swayed by busy days. Natsuki, who came to teach her brother's life during the summer vacation, takes good care of you so that you can lead a proper life alone. This is a summer story about Natsuki and you.

Casual Conversation, day spent with someone. You will remember the warmth that you have forgotten for a ling time by being with Natsuki. Natsuki works hard for you. You prepare a special view to respond to that feeling.

It's been a few days since Natsuki came, and the fun and noisy days continue. But at the same time you begin to feel a slight impatience. You make a decision for Natsuki, who still cares for you even if you show her tiredness and pity.

Natsuki spills his true feelings on your cold words. Your younger sister, who cannot be honest, and you, who are stubborn, will know each other's thoughts for the first time. Eventually, the small but important days have come to the end of summer vacation.

You and your childhood friend Moeka, who reunited in Tokyo, are spending their days enduring the harsh conditions for each other's dream. Such a lonely person snuggles up and gets a litter warmer, this is a story of Moeka and you in a certain autumn.

Moeka supportsyou with a smile when you take a step toward your dreams. It's a fun time for just two people like when I was a kid. However, on the other hand, Moeka is worried about the reality that emerges. A slight gap was beginning to appear in their steps.

Moeka hits you unchanging kindess with inevitable irritation. In addition, I get sick due to daily strain. You who care for you and Moeka who shows weakness. A gentle moment will make Moka make a big decison.

A quiet town where you can't hear your usual singing voice. Boring days without Moeka. Eventually you start walking. In order to fulfill the promises we have made, we spin words with thought. When that word arrived, Moeka again--

You and Yui spend your first summer together. Yui playfully frolics on the beach and you two become even closer.

You and Yui become closer, but something seems off. Yui does something rash after she realizes something feels off between you two, which leads to your first fight.

Yui starts sulking and acts rather jealous all the time, but you tell her how you really feel. Despite the supposed strains in your relationship, in the end, this should all make your bond even stronger.

You and Yui enjoy a trip to a ryokan at the end of summer. Your bond together is even stronger now. That night, under the starry sky, you and Yui share an unforgettable moment.

You live and work at a bathhouse that’s in danger of going under and get worked to the bone by the owner's granddaughter, Minori. You’re both very close friends, almost like brother and sister, and another fun-filled day is about to begin.

You and Minori go to a local summer festival. Somehow, Minori frolicking in her yukata makes her seem a little different than usual. That night, you both enjoy the fireworks and then have a serious conversation.

Minori decides what she wants to do in the future, but she realizes how difficult that will end up being. She doesn’t want to change, but she realizes she has to. The solution that Minori comes up with ends up shocking you...

You somehow agree to go along with Minori’s experiment of how it would feel if you two were married. She then tells you why she wants to protect the bathhouse, which ends up making the bond between you two stronger.

You end up running into a college student named Amatsuki Mashiro, who lives in the same apartment building as you. Your first encounter doesn’t go very well and she ends up calling you “Mr. Pervert,” but this leads into a more meaningful relationship.

Mashiro spent most of her life concentrating on gymnastics and is now troubled because she feels like she can’t do anything else. You then help her with practicing for interviews, cook with her, and other things, making you closer. You also feel troubled about work and you two start talking a lot more.

Mashiro still struggles to find a job, but then you end up finding the perfect job for her.

Mashiro thanks you for helping her move forward, which brings you happiness as well. The girl who loves gymnastics and her “Onii-san”... Where will your story go next?