Nebula Mask Machine Man

Travelling in the spaceship "Space Colony", Nick, with the help of his ball-shaped robot "Ball Boy", arrive on Earth to study the behaviour and manners of human beings for his doctoral degree thesis. Under the human identity of a young man named Ken Takase, he meets Maki Hayama, a photographer at Shukan Hit newspaper, and later saves her from a building fall. Maki was taking pictures for a scoop about a building which had been mysteriously demolished. (wikipedia)