Though, MTL was a bit confusing in terms of the whole tree thing. I will come back to read the translation.

His immortality is ultimately connected to Shi Jingzhi in a complex way. I like to say that they are almost fated to be together. Yin Ci met Shi Jingzhi when he was a child. At the time, Yin Ci almost lost his sanity, and the child Shi Jingzhi saved him. Although they were parted, Yin Ci still remembers the little boy, and affectionately called him Little Mute.

Shi Jingzhi is called a 'Child of Desire'. They were experimental subjects that contained immense desire. This desire usually led to insanity or su*cide. Usually Children of Desire died at an early age. Shi Jingzhi's obsession was to live. But after meeting Yin Ci, his desire slowly shifted to him. ;) The leader of the Ling Sect was a Child of Desire, but he killed himself in his 20s. Shi Jingzhi's illness was because as a Child of Desire, his immense amount of internal energy couldn't be contained in his body. His secret identity was as a prince of the kingdom.

It's funny since their lives literally are connected at the end.

They were total opposites of eachother, absolute evil vs absolute good. Yet setting their differences aside, they had many interests together. Here's an excerpt:

"It's useless for you to wait here, and it's useless to pretend everything is fine. I haven't had some bullsh*t enlightenment, don't you understand? I won't help you. I never intended to save you from the beginning."

Kongshi remained unmoved, continuing to recite sutras as before.

"You will die here with your corpse exposed in the wilderness, unattended, cursed for a hundred years. You... "

Yan Budu didn't even blink his eyes. He released his grip on Kongshi's face and l**ked his lips. His tone revealed a slight wavering.

"... You're a monster. Are you truly an emotionless and heartless stone?"

Kongshi halted his silent recitation and casually replied, "I confess, this humble monk enjoys eating apricots. It can be considered a preference shared by some living beings."

He slowly smiled again, revealing a hint of bitterness in his smile. "So that's how it is. A whole month, with thoughts and emotions exchanged... It was all in vain. I was the one who went too far."

He had exposed his true intentions and worked so hard, but in the end, it was all self-indulgence. In the presence of this person, there was no such thing as closeness or distance in human relationships.

"Kongshi, from the beginning, the 'me' in your eyes was never really 'me', was it?"

Whether Yan Budu was a three-year-old child or a hundred-year-old elder, whether he had hidden motives or was naturally wicked, he was nothing more than an ordinary stone in this person's eyes.

From the moment Yan Budu stepped into the cave, Kongshi's attitude had never changed even a bit, not one bit more or less.

Indeed, equality among all sentient beings!

"People all say that I am the most heartless one. But now it seems that you, Venerable, surpass me in that aspect."

I still don’t get why ML has the physical constitution to become a root, like where did he come from? Why did his body react the way it did to the immortal wine? Also, for MC, I still don’t get how Children of Desire are created. Like are they natural born ‘monster material’ imbued with desire from birth??

Yin Ci is three hundred years old. He wants to die but he can't... even if he is decapitated. He is extremely powerful but has no inner force.

Shi Jingzhi has a weak body but extraordinary inner force. For unknown reasons, he chronically coughs up blood and has about a year left to live.

They both believe the shirou (NU calls it vision flesh) will help them achieve their goals. They use each other to travel the country to search for the shirou. They end up in dangerous situations time and again. Throughout this time, they enjoy teasing each other and develop true feelings.

It turns out that YC had saved SJ when he was a child. SJ was left in the woods to see if he would survive. YC was at a mentally unstable point at this time but SJ's presence helped YC stabilize. YC wanted to raise SJ but SJ was taken back home and a substitute mauled body was used to trick YC. YC thought SJ was dead and SJ's memory was wiped of the incident.

YC's true identity was that he was one of the founders of the nation. 300 years ago, he was a general who helped the first emperor form the empire. However, afterwards there were droughts and other hardships for the empire. The other founder, He Cheng'an convinced the emperor to sacrifice YC. Without YC's knowledge, he was sacrificed and buried under a formation to stabilize the north. After many years he was able to dig himself out but had lost his memory.

SJ is a prince but considered a monster by his family. He is a genius with intense desires. It's later revealed that he is a child of desire. Children of desire were "created" by the Imperial Preceptor to produce the ideal emperor. There were failures before but SJ is thought to be the most promising one.

Overall, there is something called a Hanging Tree. It can control the environment for good weather for the country. In return, it sucks the vitality of the people and treat them kind of like cattle. If a person eats its fruit (the shirou) they can communicate with the hanging tree and be a "true immortal", living for hundreds of years. The founders had wanted to trick YC to become the immortal but YC ended up becoming a part of the tree instead. That's why he has no inner force and can't die.

So, the IP made a mini version of the hanging tree and created the children of desire. Once the perfect child of desire was created, they wanted him to eat the shirou to become a true immortal and serve as emperor.

Of course, YC and SJ ended up ruining their plans and instead lived a carefree life smooching off of SJ's brother emperor. The emperor didn't know the true purpose of the IP's plan so was semi-grateful for the rescue.