For Gabe Fisher, Thomas Bayly, Luke Hardy, Chase Marshall, Parker Davis, Ryan Voss and Ethan Andrews it was truly a life-changing transition.
Buchanan, a 6th degree Kempo Karate Master, who opened Mile High Karate in Tauranga 17 years ago, said there is alot of preparation.
"They go through a prep cycle that takes eight weeks and those are two-hour classes, twice a week and they are really intense.
"They then get to the Friday before testing and do a full day at school or work. They show up here at 6 o'clock in the evening, they train with our senior students until about 10 and then they go right through the night continuing training.
"They do a 10k march, they go up the Mount and see the sun rise. They train all the way through until 10 o'clock the following morning, when they meet up with the rest of the students down at Memorial Park, and there is another two hours for them down there."
Buchanan says all martial arts are 90 per cent mental and 10 per cent physical.
"If you control the mind, you control the body and you can ask the body to do whatever you want it to do.
"Part and parcel of the prep cycle is we have gone right back to the start and revisited everything to make sure they are competent in all the things they have learned in the five years building up to it.
"On a physical, technical level they really know their stuff. But the character things they are being taught along the way, how to be focused and how to be disciplined, well this is their opportunity to kind of prove it.
"When the going gets tough, and boy is it tough, we keep going."
Luke Hardy, 17, who earned his second degree belt two weeks ago, says it has changed him for the better.
"I remember being that kid who couldn't be bothered and now I take on a lot of responsibility. It is really motivating and has given me confidence. Goals are achievable."
It is not just a boys' own club.
Three of the four students who attained their second degree black belts were female.