I had the opportunity to talk about Tajima no Kami’s character design in an interview for the FGO USA.
The British gentleman style mentioned in the interview can be seen in the Material VI book.
Additionally, illustrator Kuniharu Komiya drew him very elegantly in the 2018 CBC Craft Essence “Chaldea Special Investigation Unit.”
I would be delighted if you could take a look at them as well.