Imagine: Tatsu after she kills you.
It was a mercy kill.
You were dying anyway.
You asked her to.
No matter how hard she tried to push her last memory of you she couldn't.
The day that Tatsu put you out of your agony still haunted her and she assumed it would until she could join you.
"I miss you, Y/N."She spoke to her sword."And I still love you."