A post was put on Facebook calling for a guide who would run alongside Apaapa in the half-marathon distance because there was a possibility he could go off course.
Despite completing the 72.9km Ring of Fire Ultra last weekend, de Monchy was happy to support Apaapa in this weekend's run.
He was not expecting to run in another event so soon but said it would be a good opportunity for a recovery run and to give back to the sport.
De Monchy said there was "no reason" athletes with disabilities should not compete in mainstream events.
"We are all part of the same community. I'm just hoping I can keep up with Te-Huia," he said.
Apaapa's foster mum, Dawn Staples, said the Pay What You Want system was a "big drawcard" because money was tight for the family.
Staples said running was something Apaapa "loved to do".
"With his disability, he can build up a lot of energy so running is a good energy releaser."
She said having people volunteer to be a guide for her son was "fantastic".
"They give up their time and it really is much appreciated."
Entries for the Pay What You Want Tauranga Half Marathon had more than doubled since the new payment system was introduced in January.
Almost 1500 runners of all abilities will gather at Fergusson Park on Sunday ready to take part in the half marathon, 15km, 10km, 5km or the Matua Mile events.
Event organiser Luke Garea said there had been a "mixed bag" in entry payments but was happy to see many first-timers.
"If we get the chance to give more people a great day on Sunday because of Pay What You Want, and in turn more people are sharing the love and encouraging others to come to the event, and we haven't gone bankrupt, it's a win".
Anyone wanting to join Achilles International as a runner can go to achillesnewzealand.org for more information.
Tauranga Half Marathon winners:
2017 Craig Kirkwood (1:12:16) and Jess Ruthe (1:17:07)
2016 Ben Ruthe (1:11:23) and Esther Keown (1:20:38)
2015 Ben Ruthe (1:10:12) and Jess Ruthe (1:17:53)
2014 Kyle McDonald (1:10:06) and Lisa Robertson (1:16:23)
2013 Tony Payne (1:10:56) and Jess Ruthe (1:17:01)