The protagonist traveled through time to a "child of heaven", but unfortunately, this child of heaven was made semi-crippled.
Setting one is that the protagonist has one pair of eyes, the left eye looks at the future and the right eye looks at the past.
Setting 2: The left eye was gouged out
It is set that the three protagonists thought that they had time traveled inexplicably, but the social background at that time allowed them to travel at will.
The fourth protagonist is set to be a beauty