Kikou Sentai Edelstein

The protagonist meets a well-known senior at the high school he enrolls in.
He's not particularly good-looking, and in fact, his white coat and glasses give him a mysterious air.
For some reason, the senior is the object of admiration from the female students.
According to his friends, he's a world-class genius.
Without warning, the senior taps the protagonist on the shoulder.
And then he says just this:

"Would you like to be my pink?"

"Yes?"

From that day on, evil fighters appear, ignoring the protagonist's wishes, and the protagonist is inevitably drawn into daily battles.