Solo carriers
 

Last night I was patrolling that slot between the eastern tip of Shikoku and Honshu (just near Gobo) and my sonar guy yells out contact, it was in a good position for an easy intercept so we headed on over and put the scope and boy what a shock I got, a Shokaku class carrier just meandering along at 4 knots, absolutely no escort. I launched 4 fish from 4 kilometers away and watched the fireworks, I seriously doubt anyone got off the ship alive it was so quick.

But I was pretty amazed!! Would this be normal for such a high-priority asset to moving around home waters at 4 knots with no escort whatsoever (granted it was night time though)?

Nope
 

Absolutely not. This is an example of random group generation by the game. It is a poorly planned event. Are you running with mods or out of the box?

Straight out of the box. Actually, I have a Japanese version Vista (inside help mabye?) so I don't really want to muck around with mods to much as my reading skills (in Japanese) aren't perfect.