Boom! Title drop at the end. Actually roll credits.
The title now hits differently after the final twist. It is indeed a complicated 4-koma about siblings. Despite all the escalating insanity, I was surprised it didn't go full dumpster fire with Nee-chan announcing pregnancy to drop the bomb on them all. But that won't work anymore now that they're all blood related. Now it's gonna be a race to who has his firstborn kid
Both father and son escapes death by Nice Boat due to the malicious spirit of Abe guiding them to safety for entertainment from the afterlife.
Wow. It all started when an unassuming-looking man turned out to be a four-timing scumbag with a secret harem, who sired seven children including one son, who then outdoes him by blundering his way to form his own (previously unwanted) harem of six, all of whom are his blood-related sisters.
Well, at least Kouta's ED is less of a problem now since he can now get aroused with more than just one girl...
inb4 this becomes a legendary classic to be discovered and studied by archaeologists and ancient literature experts in the far future...