Otomodachi Robo Choco

"Nagamori Tomoka, you have been chosen as Choco's 'friend'. Nice to meet you, okay?"

As a human weapon, she protects the Earth from giant life forms.
On one of those days, Nagamori Tomoka met a single 'girl'.
Robot. The girl personally introduced herself as such. According to the shady, doctor looking man beside her, her name seems to be 'Choco'.
Choco seems to have chosen me as her 'friend'.
"Tomoka, I have a question. What is a friend?"
Don't you know.
...No, wait. Do I know the meaning of that?
In a way, she was an existence that was more unrealistic that a giant robot. A machine with eyes prettier than any human.
This is the meeting between Choco and I.

(Source: Translated from official description)