Don't speak japanese, but as this is the third of the series and considering what happens in the 4th one /g/570077/cd18e5392f/ it's not too hard to work out.
The first one /g/569745/131ae1be2b/ shows the MC finding out about the NTR and the 2nd one /g/539785/7ffdf0dad6/ starts showing how she ended up becoming the bastard's sex toy. In this one she has sex with him again in the gym storage room at school, much like they did in the 2nd one, and at the end he asks her to meet with him outside of school so they can do it without having to worry about the time taken or getting caught. At the end the MC seems to ask her if she wants to do something with him tommorrow and she remembers what the bastard said and tells him she's busy, prioritising the other guy over the MC. And the 4th shows her going to a love hotel with the guy. That's how I understand it. Though I may be proven wrong if some wonderful person decides to translate these. :)
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