Guess this is what happens when I bottle up all thoses years of heat.

It was meant to be a simple visit for lady Sora, as a favor from Senko to keep Nakano company every few days while she was away on other business. However, one visit happened on a day that Lady Sora was going into heat herself, and while she was able to keep a lit on it every other year, this time was different as the way Nakano kind treatment towards her and how he went out of his way to entertain her with many simple things kept chipping away at her resolve, until the floodgates burst open and all those hundreds of years of pent up heat took over, resulting in her "repaying him for his kindness", which led to a whole day of intimacy between the two, mostly with lady Sora being in charge. And not too long afterwards, and despite the precautions she had taken, she found out she was pregnant. She did break the news to Nakano and Senko, leaving the both of them in shock, Senko even more as she felt betrayed, but lady Sora said not to blame Nakano as she was the one at fault for forcing herself on him and losing control. While Senko understood, she was still a bit upset.