They spawn at random chances on all maps. So there is no such guaranteed places to farm them. You just have to farm in any mission except the very first mission (I haven't seen them in that map) called Aogiri Tree Hideout. Also avoid farming them in Disposal Facility because that map is very hard to farm alone, although there exists a chance to get Kisho Arima. 

If you need Kishou Arima, play as Ghoul on hard campaign.
If you need Centepede Kaneki, play as CCG on hard campaign.

Additional

NOTICE: This guide will only give you Quinque Shards not Chunks, and you may not always be given the shards first go. You can also gain them through PvP!
Looking for how to defeat Kishou Arima easy? Click this link: https://www.animeesports.com/showthread.php?tid=891

[Video: http://https://www.youtube.com/watch?v=D07MrvkPyhw]

[Image: https://i.imgur.com/59HjoSw.png]

Hi, previously I posted the build that I made Tier Gold 3 in just few hours of gameplay around June 2024.
But that was the one from the first beta I achieved which I played for only few hours. And now the build has gotten much more improvement since then (Last Updated in August 2024).

[Image: https://i.imgur.com/aSYK38l.png]

[Image: https://i.imgur.com/BR2PM0K.png]

Skill Order
Stringified DMG > Light Regen Armor > Stringified DMG RED +25%