Commanded by Shinji Uchino, "I-8" departed Kure harbor on 1 June 1943, accompanied by "I-10" and the submarine tender "Hie Maru". Their cargo included two of the famed Type 95 oxygen-propelled torpedoes, torpedo tubes, drawings of an automatic trim system and a new naval reconnaissance plane, the Yokosuka E14Y. A supplementary crew of 48 men, commanded by Sadatoshi Norita, was also packed into the submarine, intended to man the German submarine , a Type IXC/40 U-boat and bring her back to Japan for reverse engineering.