Another interesting thing, but it's a bit spoiler-ish so I'll put it in a tag.
Spoiler for Adachi S. Link spoilers:
Apparently Adachi's arcana actually CHANGES partway through his s. link into the
Lust arcana, which represents the more twisted sociopath side of his personality:
It's also confirmed that Adachi's link can only be ranked up as the story progresses. So if you reach a certain rank too soon, it can't be increased anymore until a certain event happens.