Broken Bond: Between Vices and Virtues (BL) - Chapter 233 - 19: Be with you [M]

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

As an ordinary human being on the earth, Tang Long was brought to the Cultivation World by a lost immortal, and relying on his amazing talent, he made it to one of the five emperors in that world. However, struck by Thunder of Nine Heavens, he lost his life. It was lucky for him to transmigrate in the human world in an intern who was named Qin Haodong. With his excellent medical skills, he became a divine doctor of traditional Chinese medicine and encountered the baby girl he made before going into the Cultivation World, whose mother was as pretty as a fairy. The little girl even asked him to find more lovers. What a cute girl…

- Description from Novelupdates

A ritual gone wrong gave him the world's deadliest Class—now all he wants is blood.Zeth stole the most powerful ritual magic in the world from a mad cultist. A Class that's fueled by the blood of his enemies and human sacrifice. One that's illegal to use, punishable by gruesome death. And now that he has it, he's faced with a choice: hide away for the rest of his life from those who would hunt him down, or embrace the power, becoming the hunter to get revenge on the murderer that stole his friends' lives.For Zeth, that's no choice at all.His enemies have to die. And he plans to use every drop of blood, eldritch ritual, and demonic summoning he can to kill them.

God plucked one of his creations from his first Earth and gave him a second chance in another one of his Earths...surprise it is in DxD! Now reincarnated as a perverted side character how will our poor protagonist handle his new identity? Well he probably wont make the choices you will want him to, that's for sure!