It tells the story of Onodera Machi who was a teacher at the high school she once attended, and a handsome transfer student Chiba Yuuto came to her class.Yuuto is the younger brother of Chiba Yuichi, Machi's first love in high school. He looks almost exactly like Yuichi in high school.

Memories of her first love came to her mind, and she met Yuyi again by chance at a cocktail party.Every time she sees him, she will think of her first love. She gradually cannot take her eyes away from her younger brother Yuuto and her first love Yuichi whom she admired in high school...

Onoderacho (Hirue Iguru), an older female who dated on the precondition of marriage, fell in love with her high school classmate at first sight 10 years ago, which resulted in the "First Love Effect" that she has always been unforgettable about her first love.

One day, the transfer student Yuuto Chiba (Yukiki Yamashita) came to his alma mater high school where he teaches in Onodera Town.Surprisingly, he is the younger brother of Yuichi (Takajo Inukai), Onoderacho's first love, and Onoderacho can't help but be attracted to Yuichi who looks very similar to Yuichi.

In addition, Onodera Town met Yuichi again dramatically at a certain cocktail party...!?

At a certain sorority party, Komachi (Hiroe Iguru) met his first love Yuichi (Takajo Inukai).Unfortunately, she drank too much and vomited profusely in front of Yuichi.The next day, Komachi suddenly remembered that Yuichi was married, and was confused about his appearance at the sorority party.

At this time, Yuyi sent a message inviting her to meet alone!Komachi felt very confused about the intention of Yuichi, who was already exposed and married, to invite him.

On the other hand, Komachi was deeply attracted by Yuuto (Yamashita Yuuki) who smiled innocently in the rain, and even began to care about his careless actions...

After being confessed by Yuuto (Yukiki Yamashita), Machi (Hiroe Iguru) realizes Yuuto and avoids it.On the other hand, although the number of meals with Yuichi (Takajo Inukai) went smoothly, Yuichi was worried about whether he was a convenient woman.

At the same time, the town’s school sports festival is imminent.One day after school, a dispute broke out in the town where I went to the sports warehouse to look for the support flag!?Yuuto arrived at Machi’s crisis….And on the day of the sports festival, Yuichi saw Asamachi and Yuuto when they were alone in the classroom...;

Komachi (Iguru Hiroe) confessed to Yuichi (Inukai Takajo) and started dating. Because it was his first love, Komachi was very excited.However, Yuuto (Yukiki Yamashita) learned this fact in an unexpected way...

During this period, Komachi’s class welcomed the education intern Wada Asako (Nagata Rin).

She looks fresh and pure, but she seems to regard Yuuto as a competitor...

Moreover, when Yuichi asked her to meet the seniors of the company, the man who appeared in front of her turned out to be the man she spent the night with...?Komachi is in an unprecedented desperate situation!?

Yuichi (Takajo Inukai), who has no news at all, is seen dating other women, and Komachi (Hirue Iguru) witnesses this scene with his own eyes.Colleague Midori (Higuchi Hina) invites her to drink in order to encourage the depressed Komachi.The distraught Komachi was so drunk that Midori couldn't bear it and contacted Yuichi to ask him to pick up Komachi.

The next day, Komachi wakes up in Yuichi's room.However, there is Yuuto (Yukiki Yamashita) in the room!?

On the other hand, the true face of Asako (Rin Nagata) is gradually exposed.And Yuu and Asako, who had narrowed the distance, actually... kissed!?

“My first love was my teacher...”

Yuuto (Yukiki Yamashita) confesses his love to Komachi (Hiroe Iguru).Yuuto, like Komachi, has never been able to forget his “first love”.However, Komachi thought in her heart that Yuuto was just immersed in the dream of “first love”, and had only forgotten her old love... She convinced herself this way.

One day, someone posted on social media that Komachi was playing tricks on Yuuto, and the post quickly spread.While reflecting on her behavior towards Yuuto, Komachi reported the incident to Yuichi (Takajo Inukai). Unexpectedly, Yuichi told her a shocking truth...!