There have been a few stories that I remember reading in the past but I'm not sure about the title...

The first story involves a scientist/physicist/chemist working in a laboratory on a secret project with a number of people, one being his wife (or girlfriend?). When something goes wrong with the project, he tries to save everyone and sacrifices himself in the process. Instead of dying, he wakes up in an alternate universe where he is turned into a woman who is also the sister of said wife/girlfriend. No one except she remembers the previous universe. I also do remember that this alternate universe is one where the bomb was never dropped on japan and technology has been altered quite a lot in this change of events. I'm sorry for the scant details; I last read this story at least two years ago and haven't seen much of it since.

The second story involves a boy with 'striped' skin where his skin is either male appearing or female appearing. The start of the story begins after he has found a chest of magic items from his passed grandmother that, once he opens, turns him fully into a girl. She becomes a powerful witch and must come to terms with who she now is. Later in the story it is revealed that her grandmother can see into the future and had chosen to cause her granddaughter's 'condition' in order to hide that she was a very powerful witch. Again, I'm sorry for the lack of detail that I am able to provide!

If anyone can help me identify these stories, that would be greatly appreciated by myself! :)