I Am Seeking Immortality in Mingke

Double male protagonist + master and recipient + no CP + gray square My name is Cain Morristo. He is an old guy who has lived for more than 150 years. A long time ago, Renya Karasuma came to me and said that as long as I cooperated with him, he would give me the immortality I wanted. I was over eighty years old at that time, and immortality had long been an irresistible temptation for me. So I agreed to him. Decades later, the organization developed a potion. It was magical and transformed me back into my twenties. But I only have ten years to live, so I won't do it! Suddenly one day, a guy who called himself System came to me and said that he could make me live forever as long as I could help him collect energy. I promised him. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.