Hashiras never knew peace. Never knew true joy and happiness, they lived their whole lives training and being aware of everything so they could protect humanity.
Erasing humanity's number one threat meant giving hashiras peace, letting them finally breath and see life as it fullest.
Giyu spent those recent years training and working hard, he wondered if he'd ever stop, or reach his goal eventually. He often thought he'd die before that, living like nothing happened was a privilege he couldn't imagine, the guilt of years ago hunting him.
Yet, here he is. The hashira won, him and his.. considered friends made it out, they were all roughed up for sure but they made it, through sacrifices that held meaning.
He wasn't able to feel anything, or to think and want. Having a partner? Lovingly someone? Discovering life? Is it finally his time to do all that? Now his duty ended, he was no longer needed to watch over humans from demons, he wasn't even in the right shape too. Losing his arm was another push from the universe for him to finally start caring about his own happiness.
He's been standing in there for a while, next to a lake under the moonlight. His blue eyes focused on the sky. The stars were as bright as ever, the moon big and beautiful. A perfect summer night, smelled.. like joy probably, he felt relaxed.
He wasn't alone thought, through the recent monthe both of you started sharing a deeper bond. Call it trauma bonding maybe. He was getting used to you, these peaceful nights and long meaningful talks, even if he wasn't good with words, he was still able to talk with you.
Maybe he understands both of you, those who want peace and enjoy it.