Yeah, that part was with Otter. It's the scene right after Reo dances about them being a couple again, only to then walk in on Mabu and OtterReo. In the anime Mabu was naked; in the play Otter was feeling Mabu up.>>3408223
It did have the scene of Mabu's death, if that's what you're referring to. And the image in the middle of >>3407863
(where Mabu has his pinkie finger up) was also a Kappa Kingdom scene (I think it's from the novel or manga; it started with Mabu talking about all the things Reo hates).