Overlord: the angel of light

Satoru and tsume are saying their final goodbyes to the YGGDRASIL world they built together. Still, little to her brother's knowledge he doesn't know of his sister's secrets and what she has been going threw, as she smiles and brush things off to hide her pain, Satoru Believes everything is fine. but what really happened to make her feel so unworthy, so distant that her brother watched her like a hawk in the real world, other than working to keep his sister alive from her illness there was something he knew was going on behind his back that he never once thought their lives could change like this