Luca Tsukino, an extraterrestrial, from the earthly satellite moon, with powers and attributes unknown, Luca looks like a human boy at first glance. Handsome with delicate features, he has striking looks, with his silvery hair and ice blue eyes contrasting against the looks of common Japanese people, as if the silver of the moon's light had been distilled on his body.
But there is something otherworldly, something about him that makes him stand out and seem not entirely human.
The extraterrestrial wants to learn about the way of humans. Most importantly what is love and affection to the human race. Since he must choose a earthling wife. For the betterment of the esper race. He must breed with a woman and have an heir.
However he can't possibly look for a perfect woman all by himself; so he pairs up with a clumsy boy, called Nobi Nobita, whose love life, ironically never really started.
But, the tables turn when Luca falls for his acquaintance, Nobita. A boy.