Ok, I totally don't get why one work with for example an already honored character, and the other no. Try to read and read again the rules, and it keeps to have no much sense to me. Or both work, or both do not.

The difference is that Shameful Display can either honor or dishonor its targets. So, when you choose targets for it, the question "can this ability affect this target?" becomes "can I either honor or dishonor this character?". And when you choose targets for Kiku Matsuri, that question becomes "can I honor this character?". The answer to those questions is different for an honored character.

14 hours ago, Khudzlin said:

The difference is that Shameful Display can either honor or dishonor its targets. So, when you choose targets for it, the question "can this ability affect this target?" becomes "can I either honor or dishonor this character?". And when you choose targets for Kiku Matsuri, that question becomes "can I honor this character?". The answer to those questions is different for an honored character.

"Can I either honor or dishonor this character?" The answer can be yes, but if later I honor a character again, it nullifying the answer. Because in that case the questions would be: "Can I either honor or dishonor it? Yes. So Can I honor it again? No".

No. The rules say that, for a target to be valid, the effect of the ability must have the potential to change its state. This does not take into account the choices you make, there just has to be one that works. An effect that can either honor or dishonor a character has the potential to change the state of an honored character. That's all there is to it.

Cards don't care about later...

It's about triggering and afterwards fulfilling as much effects as you can, during resolution of this action.

Matsuri is straightforward honor 2, so can't be fulfilled if at least one is honored, as it's a "single effect", while Shameful as two effects, so at least one need to be fulfilled and one can fizzle.

It's all aout game state change.