It is a bittersweet moment for Vulikijapani after impressing on his return to the starting line-up against Catalans Dragons on Sunday evening.
The Fijian made 20 tackles in a solid defensive showing and took 14 hit-ups for 97 metres as Hull saw off the Dragons in a hard-fought contest at the MKM Stadium.
Vulikijapani appeared to have done enough to retain his spot this weekend but he will instead line up for the Army's rugby union team in the Babcock Trophy match against the Royal Navy at Twickenham, following in the footsteps of former Black and Whites winger Ratu Naulago.
Hull head coach Brett Hodgson is philosophical about the loss of Vulikijapani.
"We’re obviously disappointed to lose Mitch this week as he was in very good form for us," said Hodgson, who was without eight first-team players for the clash with Catalans and has since lost Josh Reynolds to suspension.
"But this is a prestigious event for the armed services and a notable honour for players serving in the military who are selected for the match, so we understand Mitch’s desire to play and what this occasion means to him and his family.
"As part of our arrangement with the Army, we have certain obligations which we must adhere to, of which this is one, so we look forward to Mitch representing the club at Twickenham and hopefully helping his army side to a win.
"He is obviously gutted to have to leave his club team-mates behind this week, but he will be ready to rip in again on his return.
"We look forward to welcoming Mitch back into our squad next week and everyone at the club wishes him well this weekend."