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?

Matteo Domingo is an extraterrestrial being that disembarked on the Philippines back in the 16th century during the Spanish Colonial Era. As he ventures to aid a teenage girl, Marcella, from descending off a cliff, he failed to join his trip, the KMT 184.5 comet, back to his planet and is grounded on Earth for the next four centuries and counting. He possesses an almost perfect form, enhanced physical abilities that improves his vision, hearing and speed drastically, and has a rather caustic, jaded point of view with regards to human beings. As time passes by and the story folds on, Matteo is forced to employ a new identity every ten years, as his human appearance never ages.