MTL - Start with Batman - Chapter 364 Gatekeeper

The bad news, at least for me, is that I died. The good news is that I was reincarnated into someone else's body who lives in a cult full of beautiful women... but this cult forbids love. Well, one can't have all the good things. I thought I was safe until the worst happened. A system appeared that told me that I would die if a girl didn't accept my confession within a month... I have to get out of that cult now.Every 10 days I upload 15 chapters at once on Patreon.

Chen Sha came to a world of immortal martial arts and was ordered to take charge of the world’s first sect.

Before his death, the previous chief told him:

“If you don’t become the best in the world for one day, you are not allowed to go down the mountain for one day.”

So he closed himself in painstakingly, crossed the heaven gate in his body, and faced off against the ancient and modern powerhouses…

…

Many years later, Chen Sha recalled the day he went down the mountain,

From the moment he descended the mountain, he was number one in the world.

In the next ten epochs, any gods and demons have returned, immortals and Buddhas have lived in the world, ancient powers and ancient gods have appeared one after another.

No matter how the times change, he has always been No. 1 in the world and has never changed.

- Description from novelbuddy

A series of short stories in the world of Toaru Majutsu no Index organized into chapters featuring Kanzaki Kaori as the protagonist, going around the world and space doing missions for the Church of Necessary Evil, however, there is more than meets the eye as each incident is connected.

One chapter was bundled with each limited edition release of the Toaru Kagaku no Railgun anime DVD and BDs, with all of them together being equivalent to a single normal Toaru Majutsu no Index volume

I was nothing. A lowly omega, destined to live in the shadows of stronger wolves. But on the night of my eighteenth birthday, the moon had other plans for me. My mate was an Alpha’s son. The problem? He wasn’t the only one. The Blackwood triplets—Kael, Ronan, and Darian—each bore the same mark that bound them to me.To be Luna, I would have to survive the chaos of three powerful mates, a jealous rival who wanted my place, and a secret buried deep in my bloodline.Because being chosen by the moon was never a gift. It was a curse.