Adventure and romance manhua with a blue-haired (tied in a ponytail) female lead and a black-haired male lead

Question

This manhua is about a world where yin gives birth to children and yang fights to protect their families. It starts off with two yin siblings one with distinctive blue hair and the other with a bluish tint, I think. They are servants working at a household.

One day, the sibling with distinctive blue hair is sold off to another family, separating the two. She is mistreated in that household until, one day, a black-haired stranger helps her escape. She has multiple flashbacks of this stranger and finds out she has met him before when younger. She returns to her old household, only to find that her sibling has disappeared, taken away. She asks the stranger to help her find her sibling, and protect her along the way. Somewhere along the way, she remembers that she met the stranger before.

Also, at a market, they find a baby tiger, who is lost. I don't remember much from here, but I'm pretty sure the baby tiger was the child of her other sibling she was trying to find, because her sibling married a yang with the power to transform into a white tiger.

If I remember correctly, the manhua was in full color. That's all I remember.

Answer 1

Is this Under the Blue Moonlight...?

Haram and Hanul are brother and sister with nobody to rely on but each other. They are also Yin, beings who blur the lines of gender and are shunned by society despite being the only ones capable of giving birth to the blessed Yang. One day, Hanul leaves with a promise to come back soon. But as six months pass without a word, Haram sets out to find him, with the unexpected help of a Yang named Chong Yun...

This manhwa is set in world where there are special people classed as 'Yin' and 'Yang.' Yin can be impregnated and give birth regardless of their gender, while Yang can't give birth regardless of their gender, but can impregnate others.

Siblings, Haram and Hanul, are Yin orphans with long blue hair who were taken in by bandits and raised by in a village. They were taught magic, to make them useful, but otherwise treated poorly, as Yin are reviled as a sort of underclass.

When the siblings are young adults, the brother, Hanul (whose hair is a darker shade of blue than his sister's), is sent off to war and goes missing. After six months, the sister, Haram, gets tired of waiting for him to return, ties her hair into a ponytail, and decides to sneak out of the village to look for him. She's caught and confronted by one of the villagers, who's brandishing a knife, but is saved by a young man with short black hair, named Chong Yun, who offers to aid in her escape and accompany her on her journey. Chong Yun is a Yang prince.

Along the way, they pass through another village and buy a white tiger cub. It's later revealed that this cub is the child of Hanul and the supreme sovereign of the Tiger Clan, beings that can shapeshift between human and tiger form.

Later still, it's revealed that Chong Yun met Haram and Hanal when all three were much younger, although Chong Yun had long white hair back then.