It's Not Easy to Be a Man After Travelling to the Future (WN) - Chapter 1246: Twilight's Plan!

After causing a tech disaster in the real world, genius shut-in Rin Katsuro is sentenced by the gods and banished to Ereborn—a realm ruled by chaos, where ancient scripts control magic and dungeons feed on trauma.He wakes up in the body of a legendary war criminal—the Demon King's General—and is mistaken for the adoptive father of a demon princess.Armed with unstable “Error Magic” that lets him rewrite reality like code, Rin doesn’t want to be a hero... but when angels declare war on the demon races, and his daughter calls him “Papa,” he might just rewrite fate itself.This is the story of a broken man with nothing left to live for—until an entire world starts calling him Dad, Demon, and Destiny.

BL manhua artist, Ti Xiao, has been single for many years. As such, he is under constant pressure to find a partner and get married. His family’s little niece shipped him together with her school’s English teacher to form a CP. The editor at work also want to introduce their friend to him. One day, a new neighbour moved in next door. He couldn’t help but notice that he seemed kind of reserved and cold. After getting a glimpse of him, he was ready to make trouble. He used his numerous ninja skills to discover his new neighbour’s identity. It turned out he was the English teacher at his niece’s school! Not only did he like his work and was his fan, but he was also his editor’s friend!

- Description from Novelupdates

Being given a chance and reincarnated is nice and all, yet why do I have to become that male friend who just watches the protagonist flirting with his harem?---World: Kaguya-sama: Love Is War - Hyouka ----