hi sorry my thoughts are kinda everywhere as i try to understand kny’s messy ass timeline. but i’m trying to determine at what age shinobu actually became a hashira. long rambling under the cut.
what little we know about the tsuguko to hashira process is that the hashira train a tsuguko to take their place when they a. retire b. die. although, sometimes the tsuguko developes their own style and becomes a hashira alongside their teacher (mitsuri).
shinobu was kanae’s tsuguko, until kanae died. meaning that the next in line to take kanae’s place would be shinobu. ... but shinobu is 14 WE ALL KNOW that she can’t even use flower or water breathing effectively to cut off a single demon’s head. also, it’s unclear if she’s created insect breathing at this point or even started on the flower poison. literally, she wouldn’t be prepared at all.
this is where my headcanons come in. i want to say that by 14, shinobu has started to develop insect breathing and began test trials of wisteria poison. but they aren’t anywhere near satisfactory. so come the time that kanae passes, shinobu doesn’t have anything to show that she’s capable of taking her sister’s place. and the grief doesn’t do anything to help.
thus she asks / or is given time by ubuyashiki-sama to work on herself and come back once worthy enough to fill kanae’s role. (shinobu doubts she can, but fuck she can’t everyone down more than she already has in this depressing time)
within a year, now 15ish, shinobu has completed her breathing techinque. but still adapting to it. and has run multiple trials of wisteria poison and has the perfect formula. Now just needs to figure out the best dosage. this is when she also works with a swordsmith to develope a blade / sheathe to fit her techinque.
by the age of 16, shinobu has created and perfected insect breathing and the sweet ol’ fuck off poison we love. this would be when shinobu would finally become a hashira. i also want to flavor that having done all these test runs of her breathing style and messing with poison dosages - shinobu slew the necessary 50 demons it takes to normally become a pillar. basically making her double qualified to be a pillar in kanae’s place.
this age would also align with her appearance in tomioka gaiden, which is (if i’m remembering right) a month after giyu met tanjiro and nezuko the night of the slaughter. because in the gaiden it’s established that shinobu was already the insect hashira at that point.
I’ll probably start a part 2, but my head hurts enough trying to scramble kny’s GODDAMN TIMELINE FOR THE HASHIRA. so ugh, peace and i literally only read through this once. sorry for any mistakes.
