Warning: long and not 100% faithful, it's a loose translation and I'm too lazy to put all the context.
So there's a pair of god and goddess who are banished from the heaven and cursed into the form of a dog and a wild swine respectively. Dog god and swine goddess go their separate ways.
Later on earth, a king on a hunting trip pees on a leaf. The swine goddess, after meditation, is literally thirsty and she drinks the piss. Swine goddess magically gets knocked up and gives birth to a beautiful human baby girl. The baby girl is found in the forest and is adopted by the royal family. She grows up to be an extremely hot princess and every king and prince want her. She rejects all of their proposals like the stacy she is.
Tired of all the kingdom and politic and conflict and marriage proposals shit, Princess exiles herself for a me-time with her weaving kit. One of her tools fell and like a low-energy princess she is, she thinks to herself "Man, I would marry whoever picked it up." Somebody does actually picks it up. Guess who? Dog god.
Princess comes back to her kingdom bringing a big news. Ashamed of their daughter being into bestiality, the kingdom exiles the couple back to the forest where they live a simple life. Princess and dog god fricked (don't worry he turned back into a handsome dude that time) and has a human son. Son doesn't know dog god is dad and treat him like a family dog.
One day, Mommy wants deer liver so son with dog goes hunting. Son gets pissed because deer gets away so when he sees a fat ass wild sow he knows he can't miss it. Dog god recognises the sow as the pig goddess, which is the son's grandma. Son commands the dog to kill the pig but the dog just won't budge with everything he does. Angered, the psycho kid then kills the dog god, takes his heart, cooks it, and gives it to his mom.
After his mom finds out she actually have eaten her own husband, she was furious. She hits her son with a rice spoon hard enough to cause TBI and memory issue, then banishes him from the house. Scared on confused, the boy ran away. The mother eventually regrets it, but it was too late. She prays to the gods so they can meet again and do some fasting rituals.
Meanwhile, the son travels the world, learns many cool stuffs from cool people, and grows up to be some super strong, super handsome man. He eventually came back to where his mother was (she is granted eternal youth btw). The mother doesn't recognize the hunk being her son grown up, and the son doesn't recognise his mom due to TBI. So you know what comes next? They fall in love. Until one time Mom stroke Son's head and discover the wound where she hit him, confirming he's her son.
Panics, she rejects his proposal for marriage but he is the psycho who kills dog so of course he's pushy. Somehow, telling the truth doesn't cross the mother's head or she knows her son is dumb as shit she knows nothing get through him, so she came with a solution: she will only marry him if he makes 1000 boat and a lake by damming the flow of the nearby river, by the dawn.
Lvl 9999 Son uses his army of supernatural creatures to easily do it because of course. Lvl 100 Mom panics and do some trick like making the roosters crow, beating the mortars, and extending a giant red fabric at the eastern area to mimic the sunrise. Creatures thought it's morning already and scurry away like roaches, abandoning the project like they don't need to collect the pay. In frustration, Son kicked one of the boat and it became a mount because because (and actually many other origin myths about lical geological formations, but I'm too lazy you won't know the place anyway)
After he fails, the Son still never gives up and keep pursuing his hot mom. Mom begged the gods to not let herself taken away by him and instead of imposing a restraining order they turn her into a flower. Meanwhile the son disappears into another dimension.
The end.
There were some variations like the son realizing it's his mom he has been lusting over and begged for forgiveness from the gods (and actually got punished with. . . I forgot), but I'm not gonna mention them all.