I'm in Doraemon's World.

The boy traveled through Doraemon and became an orphan. Then he went to Nobita's school by accident and became his classmate. Then Doraemon's arrival filled their lives with fun, but all this changed after the protagonist found a book. This makes their future journey fraught with danger. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.