Since Shiba Yojimbo is an interrupt effect, will it also cancel effects that you play on shugenjas as the owner? For example, if you play something like benten’s Touch to honor a shugenja or you attach magnificent kimono or play supernatural storm or against the waves?

I guess you could use it to do that, if you really wanted. Interrupts/Reactions don't just happen, you have to activate them at the appropriate times so Shiba Yojimbo isn't just going to cancel something if you don't want it canceled. Regardless, attaching something doesn't target, nor count as a triggered ability, so you can't cancel a magnificent kimono (or more likely a cloud the mind) with the Yojimbo.

I see. So you don't have to activate it. That's good to know. I thought it was just like a trigger effect that always is on. Thanks.

You never have to activate abilities unless they say ' Forced ' on the front, like Steadfast Samurai's ' Forced Reaction '.