In the kamisama hajimemashita manga, how does a tengu reproduce if females are forbidden on the tengu mountain? The mountain only consists of male tengus!
Tengu reproduction is not explained in the manga, but Julietta Suzuki hadn't invented them. They are supernatural beings from the Japanese (shinto and buddhist) mythology, having both human and avian features.
The tengu described by the mangaka are very much like the ones in folklore. They live on a mountain in which human rules not apply and they maintain their purity, so probably the folklore can be applied here. There are various explanations in folklore on how tengu are created, the most common are:
- Tengu hatch from giant eggs. There are apparently bird tengu (crows) nesting in the mountains where tengu live.
- A tengu soul/spirit possessing an unborn child. The spirit is created when a person dies who is not wicked enough to go to Hell, but not fit for Heaven either.
Kurama Shinjirou, one of the supporting characters is referred to as the Soujoubou's son who is the king of the mountain. There is nothing said about his mother, so probably Soujoubou shapeshifted into a crow to find a mate and Kurama was indeed hatched from an egg. He has nice wings too :)