I Came to Another World and Somehow Became a Shinigami

You might not believe this, but my big sister dragged me to another world?

You might not believe this, but I became incredibly strong as soon as I arrived in another world?

You might not believe this, but there are so many wives in another world that I can't even finish chasing them off??

You might not believe this, but I turned into a girl the moment I showed up?

You might not believe this, but in my previous life I was my big sister's husband?

What the heck is this!!!!