He continued in this class until 1999 and spent the 2000 and 2001 season in the All-Japan 250cc Championship, with a shortage of big results, other than 9th place in the 2000 Suzuka 8 Hours race.

Kiyonari received a telephone call from team principal Fausto Gresini to move to MotoGP started from 2003 French motorcycle Grand Prix until the remainder of the season.

He was back for round 9, and retook the championship lead from teammate Michael Rutter, but eventually was overhauled by the improving Ducati of Lavilla and he finished the season runner up.

Kiyonari also raced in the Valencia Grand Prix for Sito Pons' Camel Honda team, finishing in the points.

However, in the double point final round at Brands Hatch, after a win in race one (he was leading when Shane Byrne's heavy crash caused a stoppage.

Kiyonari finished 2nd in the shortened race behind Haslam, thus winning the championship by 8 points.The 2007 season started at Brands Hatch, with Jonathan Rea and Leon Camier performing better on their Hondas.

In 2008 Kiyonari made his Superbike World Championship debut, having reached an agreement with Ten Kate Honda, to partner Carlos Checa and Kenan Sofuoğlu.

In September 2009, Kiyonari returned to British Superbikes to make a wildcard appearance at Croft Circuit, replacing the injured Glen Richards.

[5] 2011 saw Kiyonari stay with HM Plant Honda in the British Superbike Championship, alongside two time BSB Champion Shane Byrne.

[6] For the 2012 season, Kiyonari headed to Asia, leading Malaysian team Boon Siew Honda Malaysia Racing as they aspire to lift the FIM Asian SuperSports 600cc trophy.