Hey guys, for anyone having trouble with Hattori disappearing/not-appearing during the quest Of Swords and Dumplings, I found a way to fix it without cheating, using in-game mechanics (confirmed for other people), at least its worth a try. TLDR at bottom

*this is a repost of my own comment on someone else's forum post asking for help, (https://gtm.you1.cn/app/292030/discussions/0/1456202492170187555/#c2266941647867309129)
people found it helpful so I'm making it into a stand alone, hopefully this helps anyone else stuck on this part of the game and/or trying to 100% the game like me.

First, you must have the time set to daytime, (ie, noon, midday) the quest cannot continue since its not dark yet, at this point Hattori should be at home but he is glitched out. So, go visit his empty house west of the Putrid Grove, the house will be empty, run upstairs, then exit the house.
This whole time your quest marker should still be at the docks meeting place.

Next, run to the quest marker at the docks. Hattori should immediately spawn in and start walking home, you can't talk to him at all (a little running around in the general area may be required to get him to appear, according to others)

At this point, you can meditate there at the docks until dawn and he should show up like he's supposed to.

hope this helps someone

TLDR

1. visit Hattori's house mid-day
2. go upstairs, the house will be empty
3. run to quest marker at docks
4. Hattori spawns in, walks away
5. meditate until dawn, hattori shows back up, complete quest



PS: if you found this guide helpful please rate it so it becomes more visible and other people can also get help for this pretty annoying glitch, thanks!
PPS: Sorry I dont have any supporting pictures/video, I have since completed the game and uninstalled, if you guys found it helpful and want to submit 2 or 3 pictures you can leave a comment and we can try and sort that out