Toaru Majutsu no Index SS - Volume 2, Chapter 18: Worthy of Carrying On That Name. The First Friday of October.

Ding![The Host has died!]A system message popped up in front of Nell's body after his last dying breath.Ding![Dark Evolution has been activated to absorb the death essence of the host.]And then he opened his eyes to find himself in the past right before the battle started.'Ah! Am I back to the past?'Ding![Please choose a partner to start the Dark Evolution process.][Partner Condition: Must be a living creature from the Monster category, not the Human category][Partner Gender has to be Female.]'Partner? A monster?'Nell's heart pounded in his chest, and he felt a cold sweat coming on.'A female monster?'

Xia Yan passed through to the world of Bleach and became an eleven-year-old boy. He was rescued by Renji and Rukia in the Seireitei, and he was studying at Shin’ō Academy, and he was a student of the same class.
He is a top student of the Shin’ō Academy, and he is vying for strength by various teams. In the end, he has entered the first team of secret mobile maneuvers.
He will use punishment to kill every person who tries to threaten the martyrdom and protect his loved one.

- Description from Novelupdates

Ye Chu is a miserable supporting character from a novel (she transmigrated).

She’s the most famous socialite in Shanghai, but her existence was to emphasize the magnificence of the white lotus female lead.

In the previous life, Ye Chu died in an accident. After rebirth (still in the novel), she didn’t only want to get revenge, but also change her fate, allowing every side character to have the opportunity to shine. Ye Chu and Lu Huai are a fake couple in their previous lives but reunited in this life.

They probed each other at every turn and slowly got closer to each other. They two fell for each other and confronted their enemies together.

- Description from Novelupdates

What do you do when you wake up and find yourself inside the very game that you love?

What do you do when you realize you that you have not only become an NPC – you have even been thrown back in time to before the game even launched!

What will happen when our protagonist’s two realities coincide?

Han Xiao was a professional power leveler before his transmigration. Using his past life’s knowledge, Han Xiao sweeps through the universe as he prepares for the arrival of the players. This is definitely not your typical transmigration novel.