The quote you mention is a taken directly from the book 'The Doolittle Raid' by Carrol V Clines. In this book Clines quotes a crew member, Nakamura Suekichi, of the Nitto Maru, a small converted fishing boat, which had spotted the US task force and radioed its location to the Japanese 5th fleet. The Nitto was a part of a large fleet of similar boats patrolling the region, to warn of potential enemy carrier raids. Nakumura is quoted by Clines in a 'letter to the author', a personal account, written after the war. In the letter, Nakamura mentions that he saw some enemy planes while on watch in the early morning and went below to inform his Captain, Gisaku Maeda, who responded that they must be the ‘usual morning patrol planes from Japan’. Nakamura returns to the watch, but then goes below to inform his Captain when he sees the American carriers. After verifying the claim, and after ordering the report to be made to the Flagship, the Captain then commits suicide.

It may be that Captain Maeda of the Nitto killed himself because he had neglected to act and report when the US aeroplanes were sighted and, after spotting and reporting the carriers, the US taskforce would now certainly close in and destroy the Nitto. After the death of Captain Maeda, Nakumura is quoted as saying: ‘Since we had communicated the discovery of enemy ships and planes, we were positive that no damage could occur in Japan’. Nakamura also says that they were using their single 1 inch gun to fire back at the 10,000 tonne US destroyer that was trying to sink them. Nakamura in his letter seems to frame Captain Maeda as a coward, and the rest of the crew as ‘brave and foolish’, for reporting the location of the Taskforce, thus upsetting the American plans, and then taking on the US destroyer, knowing they would be sunk. Of the 11 crew, five survived and were picked up by the USS Nashville.

There are some inconsistencies though. The report of the Japanese crew discussing 'two beautiful Japanese carriers' and then reporting to the 5th fleet 'Three enemy carriers’ is intriguing. The IJN fifth fleet was reported to have received a message from the Nitto that read: "Three enemy carriers sighted. Position 650 nautical miles east of Inubo Saki 0630”. This conflicts with the sighting of two carriers mentioned in the Nakamura letter. The USS Hornet is reported to have spotted the Nitto Maru at 7:44am. This means that the Nitto Maru spotted USS Hornet at 6:30am, but Hornet did not spot Nitto until an hour and fourteen minutes later, despite knowing roughly where they were on radar. Nitto was also spotted by US aircraft at around 6am. At the time of encounters with the Japanese picket ships, a storm was raging. 20ft swells were reported to be occurring, with large waves coming over the bows of the carriers, and the Japanese picket ships were worried about capsizing. Visibility was reported to be down to one or two miles, which may account for these errors.

It is presumed that the Nitto Maru spotted the US Task Force in the storm. As Nitto is a much smaller vessel than the larger US ships, and would be hard for the task force to spot Nitto, even with radar, in the storm and in the early morning light. This is further reinforced by the difficulties encountered by the destroyer USS Nashville, when ordered to sink the Nitto at 7:52am The size of the target and the rough seas, among other issues, meant that it took 928 6-inch shells and 29 minutes for the 600ft Nashville to sink the 70ft Nitto.

Captain Maeda likely killed himself because he had discounted the observations of his crew about presence of enemy aircraft , the job of reporting the location of the carriers to the fleet had been completed, and their comparatively defenceless ship the Nitto Maru would now certainly be sunk by the US taskforce.

Sources: The Doolittle Raid: 1942. Americas First Strike Back' by Clayton Chun

The Doolittle Raid By Carrol V Clines.

The Doolittle Raid by Duane P Schultz.