Uchuujin Senyou Mitsuyu Route

As an operative of his organization, the protagonist succeeds in capturing an illegal alien and—through interrogation—learns the whereabouts of its comrades.

But when he arrives at the indicated location, it turns out to be nothing more than a human-run factory. Convinced he’s been fed false information, he’s taken aback when the very workers there—secretly in league with the aliens—seize him and drag him away into space.

Now, sold to the highest bidder at an alien-run auction, his fate hangs in the balance… What will become of our hero?

(Source: DLsite, translated)