Yu Feng's best friend died.
Just as he was overcome with grief, a System came to him and said that collecting enough of his best friend's soul energy could bring him back to life.
To save his best friend, Yu Feng endured traveling through multiple worlds.
To help his best friend recover, Yu Feng busied himself with caring for him around the clock. He endured that, too.
But why was his best friend looking at him with growing tenderness...?
[The story of an adorable straight guy who does absolutely anything for his best friend while trying to revive him, only to be won over by that very friend]
World One: Demon Venerable with inner demons × protector
World Two: Adopted son × gentle widow
World Three: Deluded student × powerful, cold instructor
Tips:
1. One-on-one romance, happy ending for the main couple.
2. Quick transmigration; the top and bottom are the same person in every world.
3. The top and bottom are unrelated in every world. May include (pseudo-)forced elements.
Theme: Love can overcome hardship and obstacles.
It's very interesting to watch, and I really like developing my world view.