Liger's probably it, but then again weight divisions weren't always as 'flexible' as they are now. I'd also question why a Tiger Mask never won the belt. Sure, it was a junior heavyweight gimmick, but it's a legacy mask that's had some talented guys underneath the hood, some of which were heavyweights. If Kota Ibushi ever wins it (and he should) I'd consider it a small victory for the franchised mask character.
Shibata's an interesting one because timing and regime change plays a lot into it. Hirooki Goto is considered sort of a bridesmaid for the same reason. I was never a huge fan of Goto or Shibata though, or Inoki-ism in general. If either's a tragedy for not winning it, it's Shibata just based on how much Japan loves him.