Jekyll and Hyde are twins who began changing places when they were kids after the stoic Jekyll became jealous of the outgoing Hyde. Now at school, they met the first person who could ever tell them apart, John, and the three became friends. Unfortunately, shortly after that one of the twins died, and though the gravestone said Jekyll was buried, John isn't certain which twin was left behind. This story was heart wrenching but very well written. The conclusion wasn't entirely satisfying to me, but I still highly recommend. Trigger warning: dealing with death.
Boku no Gemini