The promotion is also credited for making Rusher Kimura a major star in Japanese Puroresu and holding Japan's first steel cage match.

[9] This system rapidly proved ineffective, and after Yoshihara's attempt at seeking a partnership with JWA didn't go through, IWE transitioned to a more traditional structure with its own roster of contracted wrestlers.

The promotion was then approached by Antonio Inoki and Tokyo Pro Wrestling (TPW) to hold a joint tour titled "Pioneer Series" in January 1967.

[9] The tour was highlighted by the participation of Danny Hodge, The Kentuckians (Jake Smith and Luke Brown), Eddie Graham and Johnny Valentine.

[11] Matsuda had plans to invite José Lothario, Tarzan Tyler, Sputnik Monroe and Bob Orton for the second tour, but they didn't come to fruition.

This promotional war, later dubbed the "Osaka Summer Battle", gained a lot of attention, with JWA hosting a main event featuring Giant Baba defending the NWA International Heavyweight Championship against Gene Kiniski in a best 2-out-of-3 falls match, and IWE presenting a main event with Hiro Matsuda and Sam Steamboat facing Bill Dromo and Roger Kirby.

[19] In order to raise funds, IWE, through the intermediary of Mori, who was a friend of Yoshihara from their days at Waseda University, transferred its shares to Hiroshi Iwata, the president of a dairy company in Hiroshima, and asked him for a loan.

[18] The Great Togo, whose contract with JWA ended four years ago, was brought in to replace Matsuda as the booker for the foreign wrestlers.

[19] In January 1968, the Opening World Series featured Lou Thesz, Danny Hodge, Hans Schmidt, Waldo Von Erich, Bulldog Brower, and referee Fred Atkins.