Taiyou no Yuusha Fighbird (1991)

An evil alien life form, Dryus, assaulted the Earth. The leader of Space Patrol, Fighbird, pursed Dryus to the Earth. Fighbird combined with an android that Dr. Amano was developing. Fighbird named Hidori Ryutaro and fight against Dryus to protect the peace of the Earth. At first look, he was a normal person, but because he was an alien, Fibird, his acts were a bit away from the normal persons'. Usually, he worked for Dr. Amano as an assistant. He looked uncouth always wearing while coat and glasses. However, once enemy appears, his personality changed dramatically. (Source: AnimeNfo)