wait for Bennousuke and nabunosuke to evolve first, wait two turns then you should get Mushashi and Tadakatsu, these two are required for the ending, also wait for Botenmaru and kenshin to evolve too, you need EVOLVED heroines to get the endingNo, I checked the ending guide and I appear to have achieved all the requirements (Keiji, Kotaro, Nabunosuke and Bennousuke must be alive in the burrow and in a lewd state). I already got the ending with Nabunosuke as Tadakatsu and Bennousuke as Kenshin.
On my most recent try, here is what I did:
* Played completely defensive and only captured seedbeds who attacked (e.g. Inahime, Magoichi, Hanzo, Kotaro, Keiji)
* Triggered the appearance of Bennousuke and Nabunosuke by attacking their castles, then captured them the next turn
* Only used food when their insanity event triggered so as to avoid them dying
* Did not use food to lower their sanity, instead only relying on breeding
* Did not attack anyone else
And still no go. At this point, I'm just trying stuff out to see if there's some sort of event that needs to trigger.
Has anyone gotten this ending using the English patch? I wonder if I need to use the Japanese version to trigger the ending. Alternatively, I'm also going to try making the four of them mate with each type of goblin at least once.