9 IJN submarines are on station evenly spaced from the Mexico border to Seattle, and three submarines are in the Hawaiian Islands scouting. there is some evidence that one or more of these were spotted, but the sightings were dismissed or not confirmed. This was one of the great debates inside IJN on the strategy: to send or not to send the subs. the pro view was that the intel was needed on ship movements, the con view was that if they were spotted it would alert the Americans. Ultimately they were sent, but no confirmed sightings, until the actual day of the attack were made, and even then were not taken seriously.
Nagumo is approx 600 miles from Hawaii and steaming east in heavy seas, about to make a turn to the southeast that will bring him to 200 miles from Oahu. He will do one more refueling from his remaining tanker, leave it behind, and then increase speed to 24 knots. Leading the way are a light cruiser followed in a fan by four destroyers. They have been given orders to sink any ship they see, merchant or otherwise. Following the destroyers three miles astern are three fast Battleships. Four miles to starboard and port of the battleships are the heavy cruisers Chikuma and Tone that are to play a key role in Midway a few months later. Three miles behind this formidable group in two parallel columns come the six carriers, with Akagi in the lead. Bringing up the rear are two destroyers.
I believe the Kido Butai only had two BBs, HIEI and KIRIMISHIMA. Did I miss one?