Ah yes, he who fancies himself the hunter is instead the hunted...Or rather, the both of them were prey from the very beginning?
Heh, that was a great ending. "Oh we're going to miss the last train"? Oh you poor fools, surely she had already taken that into account and by the time you were done, the last train had long since gone...
More like they're heaven-bound (or perhaps hell-bound) for a different type of 'Train' ... for want of a better term, the "MMF (Male-Male-Female) Threesome Special".
At least Shinji got to climax inside for his first time, and it seemed that Suzuya-sensei Approved of his (a-hem) "girth" ... as Tatsuya said on Page 14, "You Lucky Bastard!" However, having underestimated Suzuya-sensei (i.e., he thought here's an easy lay), Tatsuya sowed the wind, and by the close he (and Shinji) reaped the whirlwind. High Probability of Snu-Snu ... Engaged.