日高郁人
In December 2000, Matsui made a return to pro wrestling at the Inoki Bom-Ba-Ye event, teaming with The Great Sasuke to defeat Akira Shoji and Caol Uno. He also competed in Battlarts, beating Ikuto Hidaka, and in New Japan Pro-Wrestling, wrestling Kendo Kashin in a losing effort for the IWGP Junior Heavyweight Championship. The same year, he faced Kashin again in All Japan Pro Wrestling, wrestling under the name of "Mr. Problem" and wearing modified Kendo Kashin attire and mask. Matsui had also stints in Pro Wrestling Zero1 and in Inoki Genome Federation.