Don't feed the Space-Time-Manipulating-Cat

When Gakushuu visited his brother, Karma fed a sparkling blue cat that suddenly transports them to a world where their parents were still married, the moon never exploded, and Ikeda was their PE teacher like they landed themselves in a budget slice of life anime.

Their counterparts aren't so lucky when they look at the sky and find a crescent moon.

Pt 4 of That universe where Karma and Asano are brothers and everyone else suffers because of it.