https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1279680/
C-4 is a plastic explosive substance similar in structure to Semtex that is used by both military and terrorist organizations. It has a reputation for producing a buzz as well as a bang.
In November 1943 I-29 departed Kure for Singapore to pick up a cargo of tin, tungsten, zinc, rubber andquinine. She departed Singapore in December 1943 for Nazi-occupied France, and reached the Bay of Biscay in March 1944. She was escorted by German warships and aircraft and came under heavy attack by Allied aircraft, but arrived safely at Lorient. I-29 departed Lorient in April 1944 with considerable German technology, including a Walter rocket engine and plans for the jet-powered Me 262 and the rocket-powered Me 163. She arrived at Singapore in July, but was sunk with her cargo en route to Japan in the Luzon Strait by the American submarine USS Sawfish on 26 July 1944.
In June 1943 I-8 departed Kure with plans of the IJN's Type 95 torpedo, a reconnaissance aircraft and submarine equipment, and collected a cargo of tin, rubber andquinineat Singapore. She also carried a spare crew of 48 men tasked with bringing back a German U-boat, U-1224, which the Kriegsmarine had transferred to the IJN for examination and reverse engineering. She arrived at Brest in August. I-8 departed France in October 1943 with a variety of German technology, arriving at Kure in December after a round-trip voyage of 30,000 miles (48,000 km).
https://en.wikipedia.org/wiki/Yanagi_missions
https://en.wikipedia.org/wiki/Japanese_submarine_I-8
On 26 March 1944, during a cruise into the Indian Ocean, I-8 torpedoed the 5,787-ton Dutch freighter SS Tjisalak. The submarine surfaced amid the debris field and after a brief exchange of gunfire with the ship's defensive armament, collected the survivors on the submarine's deck. Shortly after the freighter had sunk, the merchantman's crew and passengers, totalling 97, were tied in pairs of two and then attacked by Japanese sailors, during which they were slashed with swords and beaten with monkey wrenches and sledgehammers before being shot, then kicked into the water. Six men managed to survive and found a life raft. They were later rescued by the Liberty ship SS James O. Wilder.
Two months later, I-8 was involved in another atrocity when she struck the 7,176-ton American Liberty ship SS Jean Nicolet with two torpedoes. The 100 crewmen abandoned their burning ship and took to the life-rafts. Again, the survivors were gathered on the submarine's deck. The massacre took several hours, as they were made to walk one at a time past the conning tower, where they were murdered. When an aircraft approached, the submarine dived, plunging the remaining bound prisoners into the ocean, where most drowned. Sources differ, but it is believed 23 men made it to a life raft, from which they were picked up by the armed trawler HMS Hoxa 30 hours later. Five prisoners were taken to Japan by the submarine; one of them, Francis J. O'Gara, was found alive in a prison camp after the war. A new Liberty ship, SS Francis J. O'Gara, had been named after him, making O'Gara the only living person to have a Liberty ship named after him.
Watch that little pacman mouth on the cloud, it looks like the area "shielded" by the grain silos