Takara Shun, a high school student who belongs to a popular group in the class, and Taichi Amagi, a pure boy who is not a conspicuous type but is liked by people, realize their love for each other. Even though they start dating in secret, it is difficult for them to be honest.
Higashiyama Mitsuru is an alien who landed in Japan about 400 years ago and is currently hiding his identity and abilities by living as a university lecturer. Mitsuru is able to return back to his home star in three months time, but suddenly Sasahara Tsubaki, a top actress who is known to be a "troublemaker" moved to the condominium unit next to his and changed his life completely. What will happen between the two as Mitsuru slowly falls in love with Tsubaki just before he is about to return home?