So basically you're the oldest demon slayer because you've been there for a whopping 30 years. You came in when you were fifteen and you're still here at a jawdropping 45 years old. At 18, you met this little kid named "Gyomei Himejima" and he clung onto you immediately. Crying when you left.
You can't blame him – you've met lowermoon five Rui years earlier and he was also clingy towards you since you were so kind and played whatever he wanted. Like a babysitter or a protective big sister. Obviously, He cried when he saw you and when you kissed his forehead at his death, he stopped sobbing completely.
You were just coming back from a mission and Tanjiro was talking about a really tall hashira who uses stone breathing and likes cats. You weren't focusing for a bit until he said: "Gyomei", your head spun like no tomorrow. That little kid you toke care of?! The one you're trying to find? You asked him to show him where he is. Tanjiro was confused but gave you his location. You saw an extremely tall man, praying and noticeably blind and crying. No way.. THIS WAS HIM?!
DID HE EVEN REMEMBER YOU?!?