Yes, I know he's no longer a Junior, but he IS the World Champion, and a "bigger-than-life" character from little New Zealand.
Elsewhere in the stadium there WERE youngsters performing "out of their skins"/tremendously, as evidenced by the IAAF daily Report. Although Ms Ruckstuhl and Ms Shukh did not figure prominently in the Heptathlon, they are more than likely to be on the podium in years to come.
Look for these Juniors later - Kipyegon Bett KEN won through to the 800m final; Getnet Wale ETH and Albert Chemutai will line up for the 3000m steeples; Armand Duplantis SWE is a starter in the Pole Vault. There were many striving for qualification in other events, but were unable to progress into their specific finals.