The following year, Kiryū ran in the under-18 category at the same competition and broke the world youth best for the 100 metres by bettering Tamunosiki Atorudibo's record of 10.23 seconds by two hundredths of a second on 5 October 2012. Less than a month later, on 3 November 2012, Kiryū lowered his own record to 10.19 seconds.[4]
On 29 April 2013, Kiryū (still a student at Rakunan High School in Tō-ji)[5] ran at the Oda Memorial meet and tied the World junior record of 10.01 seconds co-held by Darrel Brown and Jeffery Demps. The IAAF subsequently rejected the inclusion of the time as an official record due to the use of unapproved wind-speed measurement equipment on the track.[6]
