His troops have been unbeaten in buildup games and walloped St Edmund College from Canberra 73-7 on Friday.
"We've got heaps of young bucks but we will still try to make the Top Four again later in the season," Udy-Johns said.
The loosie, who has been playing No 8 and openside flanker, is aiming to gain Hurricanes under-18 and New Zealand Secondary Schools selection later in the season.
HBHS head coach Tafai Ioasa won't be short of knowledge on the Fukuoka venue. He played for the Sanix Blues from 2008-2014.
"I think adapting to the time zone difference and the possible changes in diet will be the biggest challenges for the boys. If there isn't a western menu a lot of the food will be fish-based. There will be a few what-ifs for us to deal with," Ioasa said.
"Pollution isn't a big issue in Fukuoka like it is further north and because we are only 20 minutes from the beach I'm expecting the grounds to be sand-based and hard and fast," former All Blacks Sevens star and 2006 Commonwealth Games gold medallist Ioasa added.
His assistant coach and fellow former Magpies loosie, Karl Lowe, has also played for the Sanix Blues so he will have more recent knowledge than Ioasa on what conditions their players will experience.
HBHS principal Rob Sturch said the ideal scenario would have seen the 2017 team travelling to Fukuoka.
Last year HBHS were unbeaten in 21 games and beat Hamilton Boys' High School 25-17 in the National Top Four final.
"I've told the boys they are going because of the hard work done by last year's team. They have to give it their best shot for the boys who have earnt them the right to go."
He pointed out 10 of last year's 24-strong extended squad are in the tour party. Four of the 10, Udy-Johns, loosie Donovan Mataira and utility backs Jordan Thompson-Dunn and Gideon Kautai, were regular starters last year.
"Five Year 11 boys have come up from our under-15 team from last year and most are from the Second XV. Expect big things from our winger Michael Naitokani. I believe he will be better than Kini was last year," Sturch said referring to New Zealand Secondary Schools player-of-the-year Kini Naholo who scored 41 tries in 21 games for HBHS last year.
Naitokani scored five tries in the win against St Edmund's and five in the College Day 52-5 win against Wellington College.
"I've told the boys because they are the New Zealand representatives they will be looked upon as the All Blacks of this tournament," Sturch added.
HBHS open their campaign against Tokai University Gyosei High School from Osaka on Saturday. Their other pool fixtures will be against Nagasaki Hokuyodai High School on Sunday and Jianguo High School from Chinese Taipei next Tuesday.
Quarter-finals are scheduled for May 2, semifinals for May 4 and finals on May 5.
The HBHS squad for the Japan trip is: Latrell Ah Kiong, Sean Baker, Adam Bibby, Daemon Brough, Emil Crichton, Jacob Dorward, Tama Dunn, Ngiyaani Waters, James Green, Andrew Hayward, Damarus Hokianga-Heather, Taranaki Hokianga, Posala Hunt, Gideon Kautai, Corban Kireka, Rashaan Kupa, Arana Murphy, Michael Naitokani, Eldius Oli, Joeli Rauca, Zac Southwick, Sam Taylor, Blayze-Waiari Taylor, Ethan Temaari-Singh, Jordan Thompson-Dunn, Joeli Tora, Liam Udy-Johns (Captain), Charlie Varcoe, Hani-Ceejay Waiwai, Matthew Wilson.
