Cross the Dimensional Wall to Save You

A young man who had lost hope in life finally found redemption in the second dimension. He loved everything about that world. Until one day a little girl fell from the sky and asked, "Do you want to go to the second dimension?" "Of course, let's go." The young man's dead heart seemed to be ignited. "What do you want to do?" "Go and save them so that the ending will no longer be miserable." "You are such a kind person." "Maybe, but I think the word miserable suits me better." "You will meet what you want." "Good luck to you." (This book is semi-relaxing, but the main plot may be a little heavy. It starts from the re0 world, and will travel to multiple worlds in the future. If there are animations, the anime world will be the main one. When the protagonist develops to a certain level, he may also write original worlds to intersperse them. I am a newbie, so please forgive me for my poor writing skills.)