I went to Shinagawa aquarium today. It has nothing on Osaka or even Nagoya but still well worth the visit for me. Bonus points if you spot something familiar in the first photo.
Dolphin show and seal show
I have no idea how Horseshoe crabs survive in the wild. Walk a bit, stack it, wriggle around on back exposing soft underside to any passing predators for a good minute or so, repeat process.
Octopus
Mean looking shark that has very interesting although somewhat evil looking eyes
I will leave there so I don't give it all away.