I Thought He Was a Grim Reaper, but He's Actually a God-Tier NPC

[No System + Mild Horror + Nearly Invincible + Infinite Flow + One Female Lead (the CP isn’t fixed for now. There may not be one in the end, or there may be. Who knows?)] (There is one female lead. For context, the male and female leads have been together for a long time. The second male lead likes the male lead and keeps sabotaging their relationship. The couple makes a bet with him: the male lead’s memories will be erased and he’ll be sent to a random world. If he falls for the second male lead, the female lead will leave; if not, the second male lead will leave. That’s how chapter one begins.) Tang Yimu originally thought he was just a soul reaper who had to complete his assignments. But later, he discovered that he was actually an NPC in a horror game. So he escaped from his own instance and arrived in the System lobby, where his path to near-invincibility began. There were ghost familiars, mermaid tears, and yin-yang puppet shows, and he also unlocked gameplay from other worlds.