Cruiserweight Champion at the time Chavo Guerrero in a non-title match. On the March 11 edition of SmackDown!, Funaki participated in an 8-man cruiserweight tag team match teaming with fellow cruiserweights Rey Mysterio, Último Dragón and Billy Kidman against Tajiri, Akio, Sakoda and Jamie Noble. At WrestleMania XX, Funaki participated in a Cruiserweight Open for the WWE Cruiserweight Championship but was pinned by Jamie Noble.
Funaki lost the championship to Chavo Guerrero in a six-man Cruiserweight Open match at No Way Out 2005. Since then, Funaki has mainly been an enhancement talent for new and returning talent. At Armageddon 2005, he lost to Jamie Noble in a match on Heat. During an interview with then Cruiserweight Champion Kid Kash on an episode of SmackDown!, Funaki was assaulted by Kash, who gave him a brainbuster onto the interview platform.
At the 2006 Royal Rumble, Funaki faced Kid Kash in a match for the title, when he was entered into a Cruiserweight Open along with four other former Cruiserweight champions, inclduing the champion Kash. Funaki was pinned in this one fall match by then Raw superstar Gregory Helms, who won the match and title. At No Way Out 2006, Funaki participated in a Nine Man Cruiserweight Match for the WWE Cruiserweight Championship but Helms retained the title. Since that time Funaki, would regularly team with Scotty 2 Hotty during episodes of Velocity and SmackDown!. During one such Velocity taping, however, Funaki suffered a 2nd Grade concussion, where he was unconscious for just under two minutes. Funaki would resume wrestling later that year, forming a tag team of sorts with Scotty 2 Hotty, which was mainly used to put over debuting wrestlers or tag teams.
Funaki made a one off appearance at the Puroresu King Indy Summit, on December 31, 2006, reuniting with Kai En Tai DX in what was being billed as a Kai En Tai DX Revival Ten-Man Tag Match; Funaki reteamed with Taka Michinoku, Kaz Hayashi, Dick Togo and Men's Teioh to face five other wrestlers. Funaki returned to WWE TV on February 16, 2007 on SmackDown! in a brawl that involved the other SmackDown! cruiserweights and the then-Cruiserweight Champion Gregory Helms.
At No Way Out 2007, Funaki participated in a Cruiserweight Open match for the WWE Cruiserweight Championship but was pinned by the champion Helms. On May 18 edition of SmackDown!, Funaki was made short work of by recently returned superstar Mark Henry. On the June 29 edition of SmackDown!, Funaki got a shot at the Cruiserweight title against Cruiserweight Champion Chavo Guerrero and Jamie Noble, but came up short. At The Great American Bash, he participated in a match for the Cruiserweight Championship which Hornswoggle won. On December 14, on an edition of SmackDown!, he wrestled in a squash match against Edge. He also made a televised appearance on January 4, 2008 edition of SmackDown! where he lost to Chavo Guerrero in a Beat the Clock match.
On October 10, 2008 Funaki revealed his full name (in kayfabe) to be "Kung Fu Naki" during a backstage segment with R-Truth. This was used as the basis for a gimmick change for Funaki; he then came to the ring dressed in a gi and tweaked his moveset to incorporate theatrical martial arts moves. His first match as Kung Fu Naki saw him scoring a pinfall win over Montel Vontavious Porter (MVP) and Shelton Benjamin in a tag team match with R-Truth. Kung Fu Naki defeated MVP on the November 14, 2008 edition of SmackDown when The Great Khali interfered and distracted MVP. His first lost was against Edge (then WWE champion), however, he almost defeated him. He teamed with Jimmy Wang Yang against John Morrison and The Miz on an episode of ECW, in which they lost. Kung Fu Naki has not competed since.