I visited the memorial in 1969. There were indeed quite a few Japanese tourists. But, they were on the whole pretty quiet. They took photos, of course, and spoke with one another quietly.
I didn’t speak Japanese, so I have no idea what they were saying. For all I know they could have been saying: “After this, we deserved Hiroshima and Nagasaki;” or, they could have been saying: “This is where we spanked the round-eye Yankee imperialist dogs big time. Banzai!”
I’ve been to the Memorial on several occasions. From what I observe, all the Japs do is use the ship for a photo op/selfie.
On our last trip, in the theater, having been told to turn off the cellphones by a Park Ranger, one Jap woman spent the majority of the 30 minute documentary shown prior to going to the Memorial, chatting like a magpie, loud enough to turn heads. She just smiled and continued her conversation.