Anehara ~Until My Sister-in-Law Gets Pregnant~

Or perhaps a bit more precisely, it's all that matters to the family patriarch, whose desires and instructions will likely not be questioned by anyone (based on some flashback scenes in this chapter).

@MHM-Dono:
The patriarch is a tyrannical bastard, for sure, but he has irrefutable genetic logic
on his side. If Ryouko is going to give her father-in-law a grandkid with the proper
genetic profile, she must allow herself to be impregnated by one of her husband's
close relatives---preferably a brother, as in this case. Ryouko knows this, so she is
pleased to discover Haruo has a big cock, which will at least make the experience
more enjoyable when she performs her "duty."