Kai is shown standing and working out hard as he makes considerable progress in just the short time he has been at the brain injury unit in Liverpool.
Moved there last month after eight weeks in a coma at Canberra's ICU, the 23-year-old's parents Martin, Yuki and his sister, fellow BMX'er Saya also contemplated how close he came to losing his life in the accident at the Bathurst February world cup round.
"I don't think he (Kai) realises how incredible (standing for the first time), how significant that achievement was," Saya said.
"I couldn't imagine life without Kai."
Kai's mother echoed her 20-year-old daughter's sentiments.
"For me, it was really hard to understand what could be happening," Yuki said. "We could've lost him."
Kai's father Martin said he feels a deep connection to his son.
"The better he gets, the better I get." Martin said. "It's pretty hard. Thinking back to how it was in the early days (of his coma) is tough," he said.
Saya also said she owed it to Kai to put in her best at training, particularly just after his accident when she felt little motivation to do so.
"When Kai crashed, like within days I knew I had to get back into training. I found that it was my responsibility to do it for the both of us now."
Reiterated again in 7news' feature was Kai's motto uttered early in 2020 "one day at a time, one moment at a time. Let’s go.”
If you would like more information on Kai's fight or would like to donate to the family, click here.