Mitsuhi is a bright, cheerful and cute high school sophomore who lives an ordinary, simple life. One day, however, her parents suddenly tell her, "We're getting a divorce! The reason is that they are in love with another couple at the same time, and what's even more outrageous is that the two families are going to live under the same roof! Oh, my God! Things are really getting complicated... The other couple has a son the same age as Mitsuki, Yul, who is cool, handsome, has an IQ of 200, and is a perfect sportsman. His appearance has caused a big change in Mitsuki's peaceful life: Mitsuki is forcibly kissed by her classmate Ginta, and is made to laugh and cry by Yui's ex-girlfriend, Arisumi... What is even more shocking is that Mitsuki has fallen in love with Yui! Ah~ How could this happen!

Kouki Ishikawa is a bright, cheerful and cute sophomore girl, the heroine of this drama, whose greatest strength is her ultra-simple personality! Are you trying to undermine me?) The best thing about this drama's heroine is her super-simple personality. Despite Kouki's strong opposition, her parents remarried with Yuki's parents, and the two families live under the same roof!

Yu, who is the same age as Mitsuhiro, is a cool, handsome, 200 IQ and athletically perfect boy. But underneath his model student exterior, Yu is a toxic-talking, bullying marmalade boy. Even so, Mitsuhi fell in love with him without realizing it.

Mingko Akizuki, Mitsuhiro's best friend, is a young lady from an ultra-rich family, and an artistic beauty. Mingko always listens to Mitsuhi's worries silently, but doesn't talk much about her own personal affairs, making her full of mystery. In fact, Minako also has great troubles...

Su Wang Ginta Mitsuhi's classmate, a hot-blooded young man, both are members of the tennis club, the relationship is very good. In fact, Mitsuhi once confessed to him in junior high school, but Ginta rejected him. But when Yui showed up, Ginta seemed to be fidgeting.

Arisumi Suzuki, Yui's ex-girlfriend, dated Yui for three months in junior high school, but eventually broke up. However, Arisumi still likes Yui, so she often comes to stir up trouble, preventing Mitsuhi from dating Yui.

The president of the student body, Goshi Mikawa, seems to be frivolous at first glance, but there is actually a serious side to him. He falls in love with Minako at first sight and pays her a lot of attention, but Minako doesn't buy it at all. But Minako doesn't buy it at all. And there seems to be a secret between Goshi and Yui...