Toradora! - Volume 7, Chapter 4

A normal guy gets hit by a truck and isekai'd. Why? Because trucks are apparently some cosmic loophole. He decides to be a dungeon, because it sounds weird and interesting to be one. Is it? Let's find out.

Bored in class, Ivaim suddenly transmigrates into a world plagued with Fractured Realities.A century ago, Reality Masters suddenly arrived— bringing a wave of terror over the planet.Just as the people despaired, they began to discover “Threshold Items” which allowed them to enter the domains of these Reality Masters.They had two options starting from there :One, to become a Reality Walker— a person marked and blessed by a Reality Master, fighting by their side in order to defend against other Reality Masters.Or to become a Reality Ruiner— A person who kills Reality Masters, directly consuming and taking over the powers that they posses!However, to Ivaim, he seemed to have taken on a different path.As he looked towards his own body, he sighed as he realized that he was neither a Reality Walker, nor a Reality Ruiner.—He had somehow become a Reality Master....

She is the Crown Prince’s fiancee, but on the night of their wedding, an edict was made and she was given off to marry the crippled and paralyzed God of War.

A river song, triggered a legend of the rivers and lakes.
Tian Zun’s life motto: “My sword is the truth.”
Shen Lang’s life motto: “To serve people with morality, those who are dissatisfied are dead.”

- Description from uukanshu (translated)