Lifespan Modification: Immortals Ask Me to Help Them Shorten Their Lifespan

What? The person with the shortest life expectancy still has 30 million years to live? ! What? The immortal is actually the lowest existence? ! What? Are you practicing hard just to die sooner? ! How much life is left in my life? I'm miserable, I only have twenty days to live. This is a world where there are only immortals and immortals. People are trying hard to die because they have lived too long. Here, if you don't practice, you can only live in pain forever. And our protagonist Zhang Mochen actually has the ability to modify the life span of others: Are you scolding me? Sorry, I'm very unhappy. I'll give you a gift package worth five trillion years of life. What kind of gift should I give you? Really, you are too polite. We are all friends. I will help you lose some longevity. What? Did I shorten your lifespan? Are you going to die? Don't be too happy first. We are all good friends. How could I be willing to let you die? Come on, I will give you a few more years...