To me, the most fundamental gameplay indicator of a JRPG (in terms of genre) is the distinction between the combat and non-combat gameplay sequences, which is then further solidified by ancillary elements like what traits are of relevance in the character sheet (i.e. typically no non-combat skills) and the verbs you have available to you outside of combat.
In every game I'd classify as a JRPG, you spend part of the game walking around and doing basic interactions in the world (talk, open chest, pick up, etc.) and another part in which you get sectioned off from the aforementioned to engage in combat. Once that happens, your set of verbs changes entirely and you enter combat either through an active battle system (e.g. Tales of, Xenoblade, more recent Final Fantasy games) or a turn based one (Dragon Quest, Cosmic Star Heroine, etc.).
CRPGs have similar tendencies, but they have different types of character sheets, your out-of-combat verbs tend to be much broader, and you can usually manually engage the combat verb set, unlike JRPGs in which those are sectioned off entirely.
So, following this, Yakuza is most definitely a JRPG whereas something like Nier: Automata and Dark Souls are Action RPGs. Another one that often comes up is Monster Hunter, which in my opinion is just an Action game with light RPG elements. And Zelda is certainly not an RPG I think, unless you're taking RPG in the most literal sense. It's one of the clearest examples of Action-Adventure there is.
WRPG is such a weird concept to me. Sure, JRPG is also ill-defined but the only way I'd define a "WRPG" is in contrast to a JRPG. Action RPG and CRPG tell me a lot more about the basic gameplay conceits than WRPG would, both of which would fall under the overarching WRPG moniker most of the time.
