Toaru Majutsu no Index: New Testament - Volume 15, Afterword

REBORN OF THE LEGENDARY BEAST MASTER

When shy teen musician Kael uploads a rough demo, he never expects it to grab the attention of a rising studio. Thrown into the underground music scene, Kael must confront doubt, pressure, and his past as he fights to find his voice—on the mic and in life.Story was written 1 year ago

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

- Description from Novelupdates

Lu Yanzhou’s best friend Xie Chengze’s soul was broken into fragments and fell into those small worlds. In order to save Xie Chengze, Lan Yanzhou embarked on the journey to collect Xie Chengze’s soul fragments.

However, he made a mistake in the process of collecting his soul fragments. He fell in love with Xie Chengze’s soul fragments.

Xie Chengze said he cultivated the ruthless dao. He was cold hearted and emotionless but he has always regarded him as a brother. He took advantage of when the other party lost his memories to fall in love with him…

The end of the first world, Lu Yanzhou, who was in love with Xie Chengze, was struggling: “When Xie Chengze recovers his memories, will he beat me up?”

After the end of the second world, Lu Yanzhou, who had another romantic relationship with Xie Chengze, made up his mind: “There’s absolutely no next time! Xie Chengze probably won’t break off all relationships with me?”

The end of the third world, Lu Yanzhou was apprehensive: “I’m here to save him..”

The Nth world ended, Lu Yanzhou broke the jar and threw it: “Wait until Xie Chengze recovers, I’ll go after him. There might be a 1% success rate, right?

Xie Chengze: “…” I took the initiative so much, are you blind?

- Description from Novelupdates